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About Google Book Search Google's mission is to organize the world's information and to make it universally accessible and useful. Google Book Search helps readers discover the world's books while helping authors and publishers reach new audiences. You can search through the full text of this book on the web at |http: //books .google .com/I £du JTiia.'^z-i-'^i 3 2044 097 025 910 .jtj iC TflS GEOGIAPHY OF THE HEAVENS. AND ■ASS BOOK OF ASTRONOJIY; ACCCndEAXIU) ST A lb CELESTIAL ATLAS. " . BY EpJAH H. BTJRRITT, A. M. FIFTH EDITION. WITH AN INTRODUCTION BY THOMAS PICK, LL. D. Auibbr of tlie ClurUUftn PlukMopfaer, Ste. to the t i NEW-YORK : HUNTINGTON ANT) SAVAGE, 174 PEARL-STREET, 1242. 'b\'f^s\^i..Z.'\^,. P. J. Huntington & Co. I^ave recently published, in one small volume 16mo., suitable for children just entering upon the study of Astronomy, and introductory to the " Geography of the Heavens," ASTRONOMY FOR BEGINNERS, wuU a Map and 27 Engravings. By Francis Fellowes, A. M. '^' This IS one of the most succespful attempts to simplify sublime sci' encn to the comprehension of children. The author has enmloyed an arrangement and style entirely new, with a clear and luminoiilipen. and in rhc happiest manner. 1 cordially commend to parents, tcitetvbenb an:i Nj children, this result of bis labours."— Jl/rs. Sigourm Entered, according ^o Act of Congress, in the year 1833, by P. J. HUNTINGTON, 111 the Clerk's Cilice of the District Court of Connocticui V i 'V v\ PUBLISHER'S NOTICE. fo presenting a new edition of this work to the public, it is pro* Mr to point out several very important improTements which haye wen made. ^' Dr. Dick of Scotland, so well known both in Europe and in this eoontry, as the author of the Christian Philosopher, and other scientific and popular works, has prepared, expressly for the work, an IiUroduction on the Advantages of the Study of Astrono" nof. So far as authority and name can go to give currency to the work, and to establish the confidence of teachers in it as a proper text book, this simple fact, the publisher flatters himself, furnisnes every testimonial which can be desire;4 : beside which, the con- tributions of Professor Olmsted, of Yale College, cannot but be read with extreme interest. The work has been thoroughly revised, and the errors of for* mer editions corrected: subsequent to which, it has undergone a iborough examination from one of our most eminent maHiema- ticians and astronomers. It will be observed that several new Chapters, on the important subjects of Planetary Motion^ The Pke^ nmena of Doty and Night, T%e Seasons, The Tides, The Obliouiiy of the Ecliptic, The Precession of the JEqninoxes, 4^, have oeen added. . It is only necessary to observe the Atlas, to discover that the Plates have been engraved entirely anew, upon steel, and in a very superior and beautiful style. The figures of the Constella- tions are far more natural and spirited than those of the former Atlas. Especially, the characters which represent the stars are distinct, so that the pupil can discern, at once, to what class they belong. One new plate has been introduced, illustrating to the eye, the Relative Mugnitudes, Distam^s, and Positions of the dif- ferent bodies which compose the Solar System. This plate the teacher will find to be of very important service, and to aid him mach in his verbal explanations. The arrangement of the Plates in the present Atlas, is such, that the teacher and pupil can easily place toem, in mind, so as to have a distinct view of the entire surface of the visible Heavens. Such are the principal improvements which have been made in the work. They speak for themselves. The publisher knows not what could express his satisfaction with the past, or his hopes for the future success of the work, better than such improv mcnts. PREFACE. 1 HAVE .ong felt the want of a Class Book, which should be to the Vtarry heavens, what Geography is to the earth j a work that should exhibit, by means of appropriate delineations^ the scenery of the heavens : the various constellations arranged in their cider, point out and clai^-dfy the principal stars, according to their magnitudes aiid places, and be accompanied, at the same time, wiUi such fami- liar exercises and illustrations, adapted to recitation, as should bring it within the pale of popular instruction, and the scope of juvenile understandings. Such a work I have attempted to suppl]^. I have endeavoured tc make the descriptions of the stars so ramiUar, and the instructiom for finding them so plain, that the most inexperienced should no\ fail to understand them. In accomplishinp; this, I have relied but little upon globes and maps, or books. I very early discovered that it was an easy matter to sit down by a celestial ^lobe, and, by means of an approved catalogue, and the help of a little graduated slip of brass, make out, in detail, a minute description of the stars, and discourse quite familiarly of their position, magnitude and ar- rangement, and that when all this was done, I had indeed given the pupil a few additional facilities for finding those stars upon tlie artificial globe, but which left him, after all, about as ignorant ot their apparent situation in the heavens, as before. I came, at length, to the conclusion, that any description of the stars, to be practically useful, must be made from a careful observation of the stars them- selves, and made at the time of observation. To be convinced of this, let any person sit down to a celestia! globe or map, and from this alone, make out a set of instructions' m regard to some favourite constellation, and then desire his pupi to trace out in the firmament, by means of it, the various stars whicl he has thus described. The pupil will find it little better than a fancy sketch. The bearings and distances, and especially, the C9m* parative brightness, and relative positions, will Tzrely ble exhibitc perhaps jtwo weeks, in solving the problems, and admirmg the figures on it, m which time it has tocu turned roimd and round a hundred rimes ; it is then returned safely to its case, and some months afterix ards, or it may be the next evening, he directs his eye upwards to lecpg- raEFAv-s nize his acquaintance among the stars. Ue may find hn\t*if able to recollect the names of the principal stars, and the uncouth forms by which the constellations are pictured out ; but which ol* all tlw) positions he has placed the globe in, is now so present to his mini that he is enabled to identify it with any portion of the visible hei* vensl He looks in vain to see, ** Lions and Centaurs, Gorgons, Hydras rise, And gods and heroes blaze along Uie skies." He finds^ m short, that the bare study of the globe is one thing and that of the heavens quite another ; and he arrives at the con elusion, that if he would de profiled, both must be studied and com pared together. This, since a class is usually furnished with bul one globe, is impracticable. In this point of view also, the mapa are preferable. I nave endeavoured to teach the Geography of the heaTens in nearly the same manner as we teach the Geography of the earth What that does in regard to Ihe history, situation, extent, popula-. tion and principal cities of the several kingdoms of the earth, ] have done in regard to the constellations ; and I am persuaded, that a knowledge of the one may be as easily obtained, as of the other. The systems are similar. It is only necessary to change the terms in one, to render them applicable to the other. For this rea- son, I have yielded to the pre^rence of the publisher in calling this work "Geography of the Heavens," instead of Uranographt, or some other name more etymologically apposite. That a serious contemplation of those stupendous works of the Most High, which astronomy unfolds, is calculated above all other departments of human knowledge, to enlarge and invigorate the powers of religious contemplation, and subserve the interests of ra- tional piety, we have the testimony of the most illustrious charac- ters thai have adorned our race. If the work which I now submit, shall have this tendency, I shall not have written in vain. Hitherto, the science of the stars has been but very superficially studied in our schools, for want of pro- per helps. They have continued to gaze upon the visible heavens without comprehending what they saw. Tney have cast a vacant eye upon the splendid pages of this vast volume, as children amuse themselves with a book which they are unable to read. They have caught here and there, as it were a capital letter, or a picture, but they have failed to disting^h thase smaller characters on which the sense of the whole depends. Hence, says an eminent Englii>h Astronomer, " A comprenensive work on Descriptive Astranomy^ detailing, in a popular manner, all the facts which have been ascer- tained r^pecting the scenery of the heavens, accompanied with a variety of striking delineations, accommodated to the capacity of youth, is a desideratum" How far this desirable end is acccm- SUshed by the following work, I humbly leave to the pufdiw to ecide. Hartford, Feb. 1833. INDEX. Paw Androoteda. 35 Arieta, the Rmh, 43 Auriga, the Charioteer, 63 Argo Navis, the Sliip Ari;o, 74 Asteiioa et Cham, vel Canes Vu> caiici, the Greyhounds, * 91 Aquila et Autiooua, the Eagle and Aminous, 125 Aquarius, the Water Bearer, 135 Asteroida. 226 Anrora Borealid, the Northern Lights, 290 Bootes, tlie Bear Driver, 93 "^ssiopeia, 3d Cepheus, 41 Cetiis, the Whale, 47 Cohxnnba the Dove, 61 Cainelonardaliia, the Camelupard, ti6 Canls Minor, the Little Dog, G9 Canis Major, the Great Dog, 71 Cancer, the Crab, 76 (^icna Berenices, Berenice's Hair, 89 Corvus, the Crow,.... 90 Centaurufl, the Centaur, 98 Corona Borealis, the Northern Crown, 103 Cygnu^ the Swan ^. . . 128 Capricornas, the Goat '131 Constellations — origin of, 1 1 6 Comets , 243 Draco, the Dragon, 1 17 Delphimis, the Dolphin, 127 Dick's Introduction viii Geography, viii NaTtj^ation, ijt Agriculture, x Chronology, xi Propngation of Religion, xii Dissipates superstitious No- tions xiU Ofiys and Nights, different lengths o^ 278 Eriilanns, River Po, 61 Equiilus, vel Eqiii Sectio, the Lit- tle Uorse, or the Horse's Ilead, 1H4 Earth, *... 198 Equinoxes. Precession of, 262 Ecliptic— Obliquity of, 269 Eclipses Solar and Lunar, 215 Forces, Auractive and Projectile,. 260 Gemini, the Twins, 66 Grairitatioa. Universal Law of, ... . 257 Hydra, the Water Serpent and the Cup,...,........, 83 Bercnlc8|..... 112 Page Herschel. '^1 Heavenly Bodies, Parallax o(.... 293 Jupiter, 230 I'epus, the Hare, 60 Lynx, 39 Leo, the Lion, 78 Leo Minor, the IJule Lion 82 Lupus, the Wolf, 99 Libra the Balance, 100 Lyra, the Harp, 121 Monoceros, the Unicorn, • . 71 Mars, 223 Mercury, 183 Moon, 208 Moon— Harvest and Horizontal.... 283 Meteoric Showers, Professur Olm* sted's Reinarlis upon, 167 Orion, 66 Pisces, th« Fishes, 36 Perseus et Caput Med usse, Perseus and Medusa's Head, 49 Pegasus, the Flying Horde 133 Piscis Australis, vel Notius, tho Southern Fish, 136 Prelitninary Chapter, 25 Planets, forces by whicli they are retained in iheir Orbits, 236 Problems and Tables, 293 Refraction, 287 Sextans, the Sextant, 82 Serpens, the Serpent, 102 Scorpio, tlie Scorpion, 109 Sagittarius, the Archer, I2i Serpentariu9, vel Ophiuchus, the Serpent Bearer, 11.? Stars— variable 137 D ascertained. It was likewise by means of celestial observations that the length of a degree of the meridian was measured, and the circumference of the globe, with all its other dimensions accurately ascertained ; for, to ascertain the number of degrees betweei; any two parallels on the Earth's surface, observations must be taken, with proper iostmments, of the sun or of the stars, at diflerent sta- tions; and the accurate measurement of the terrestri|d distance be- tween any two staticms or parallels, partly depends on astronomica) observations combined with the principles and operations of Trigo- Dometry. So that without the aids of this science, the fi^re and density, the circumference and diameter of our terrestrial habita- tion, and the relative position of places cmi its surface, could never have been ascertained. Astronomy is likewise of great utility to the art of NAVIGATION; without a certain knowledge of which the marmer could nevci have traced his course through pathless oceans to remote regions — the globe would never have been circumnavigated, nor an inter- course ofiened between the inhabitants of distant lands. It is of essential importance to the navigator, not only to know the situation of the port to which he is bound, but also to ascertain with pre- cision, on what particular portion of the terraqueous globe he is at anv time placed — what course he is pursuing — how far he has tra- velled from the port at which he embarked — what dangerous rocks or shoals lie near the line of his course — and in what direction he must steer, in order to arrive, bv the speediest and the safest course, to his destined haven. It is only, or cniefly, by astronomical obser- vations that such particulars can be determmed.' By accurately observing the distance between the moon and certain stars, at a particular time, he can calculate his distance East or West from a given meridian; and, by taking the meridian altitude of the sun or of a star, he can learn his distance from the Equator or from the poles of the world. In such observations, a knowledge of the con- stellations, of the polestar, and of the general positions of all the stars of the first and second magnitude, is of particular importance ; and, therefore, a navigator who is imacauainted with the science of the heavens, ought never to be appointea to conduct a ship through the Indian, the Atlantic, or the Pacific oceans, or through any por- tions of the sea which is not within sight of land. By the observa- tions founded on astronomical science, which have oeen made in diflereift regions, by mariners and travellers of various descriptions, the latitudes and longitudes of the principal places on the globe, and their various bearin§[s and relations have been determined, so that We can now take a view of t)ie world we inhabit in all its mul- tifariotEs aspects, and direct our course to any quarter of it, either for business, for pleasure, or for the promotion of philanthropic ob- jects. Thus, Astronomy has likewise become of immense utility i& mvdt and CaMTMree^ in opening up new emporiums io^ imr X IKTROOUCTIOII inanufactures, in augmenting and multip]3M'ngthe sources of wealtlL - in promoting an intercourse between the most distant nations, ana enabling us to procure, for our acconmiodation or luxury, the pro- ductions of every climate. If science has now explored almost every region ; if Politics and Philosophy have opened a communi- cation between the remotest inhabitants of the globe ; if alliances have been formed between the most distant trit^ of mankind ; if Traffic has explored the multifarious productions of the earth and sea<;, and transported them from one coimtry to another, and, if heathen lands and barbarous tribes have been " visited wiUi the Da^-spring from on high, and the knowledge of salvation,'^ — it is owmg to the aids derived from the science of the stars, without which the continents, the islands, and the difierent aspects of our globe would never have been explored by those who were separa- ted ft-om them by intervening oceans. This science nas been no less useful to AGRICULTURE, and to the cultivators of the earth. The successful cultivation of the soil depends on a knowledge of the course of the sun, the exact length of the seasons, and the periods of the year most proper for the opera- tions of tillage and sowing. The ancients were directed in these operations, in the first instance, by observing the courses of the moon, and that twelve revolutions of this luminary corresponded nearly with one apparent revolution of the sun. But findmg the coincidence not exact, and that the time of the seasons was chang- ing — in order to know the precise bounds of the sun's annaal course, and the number of days corresponding to his apparent yearly revo- lution, they were obliged to examine with care what stars were successively obscured m the evening by the sun, or overpowered by the splendour of his light, and what stars were beginning to emerge Irom'his rays, and to re-appear before the dawn of the mornmg. By certam ingenious methods, 'and numerous and at- tentive observations, they traced out the principal stars that lay in the line of the sun's apparent course, ^ve them certain names by which they might be afterwards distmguished, and then divided the circle of the heavens in which the sun appears to move, first into quadrants, and afterwards into 12 eaual parts, now called the signs of the Zodiac, which they distinguished by names corre^nd- mg to certain objects and (^rations connected with the different seasons of the year. Such were the means requisite to be used for ascertaining the length of the j^ear, and the commencement of the different seasons, and for directing the labours of the husbandman; —and, were the knowledge of these thmgs to be oblitertued b^ any extensive moral or physical convulsion, mankind woula again bie under the necessity of having recourse to astronomical observations for determining the limits of the solar 3rear, and the course of the seasons Although we find no difficulty, in the present day, and require no anxious observations, in determining the seasons, yet. beiore astronomical observations were made with some degree of accuracv, the ancient Greeks had to watch the rising of Arctmcfits the Pleiades and Orion, td mark their seasons, and to determiae tKr INTRODUCTION. « proper time for their agncnltural labours. The rising of the star Sirtus along with the sun, announced to the Eg3rptians the period when they might exnect the overflowing of the Nile, and, conse- quently, the time when they were to sow their grain, cut their ca- nals and reservoirs, and prepare the way for their expiected harvest. The science of CHRONOLOGY, likewise depends on celestial observations. The knowledge of an exact measure of time is o[ considerable importance in arranging and conducting the affairs of life, without which, society in its movements would soon run into confusion. For example, if we conld not ascertain, within an hour or two, when an assembly or any concourse of human beings was to meet for an important purpose, all such purposes would soon be frustrated, and human improvement prevented. Our ideas of iime or succession in du- ration, are derived from motion; and in order to its being divi- ded into equal parts, the motions on which we fix as standards of time must be constant and uniform^ or at least, that any slight de- viation from uniformity shall be capable of being ascertained. But we have no uniform motion on earth by which the lapse of duration can be accurately measured. Neither the flight of oirds, the motion of the clouds, the gentle breeze, the impetuous whirl- wind, the smooth-flowing river, the roaring cataract, the falling rain, nor even the flux and reflax of the ocean, regular as they generally are, could afford any certain standard for the measure of time. It is, therefore, to the motion of the celestial orbs alone that we can look for a standard of duration that is certain and inva- riable, and not liable to the changes that take place in all terrestrial movements. Those magnificent globes which roll around us m the canopy of the sky — ^whether tneir motions be considered as real or only apparent, move with an order and regularity which is oot found in any physical agents connected with our ^lobe ; and when from this quarter we have derived any one invariable mea- snre of time, we can subdivide it into the minutest portions, t( subserve all the purposes of civil life, and the improvement® -^f^y science. Without the aids of astronomy, therefore, we should £S^p had no accurate ideas of the lapse of tmie, and should have hem oblifig d, like the rude savage of the desert, to compute our time by Hn^mlls of snow, the succession of rainy seasons, the melting of the ice, or the progress and decay of vegetation. Celestial observations, in consequence of h^ing ascertained a regular measure of time, have enabled us to fix chronological dates, and to determine the principal epochs of History. Many of those epochs were coincident with remarkable ecUpses of the sun or moon, which the ancients regarded as prognostics of the loss of battles, the detith of mcmarchs, and the fall of empires; and which are recorded in connexion with such events, where no dates are mentioned. The astronomer, therefore, knowing the invariable movements of the heavenly orbs, and calculating backwards through the past periods of time, cah ascertain what remarkable eclipses must have been visible at any particular time and place, and con- ■eqcumtly, can determine the precise date of contemporny events. ^«l INTRODCOTION. Calvisins, for example, founds his Chronology on 144 eclipses o^ the sun, and 1;^ of tne moon, which he had calculated for the puj> pose of determining epochas and settling dates. The grand con- junction of the planets Jupiter and Saturn, which occurs once in 800 years, in the same point of the zodiac, and which has happened only eight times since th6 Mosaic Creaiion, furnishes Chronology with incontestable proofs dCxhe date of events, when such phenomena happen to be recorded. On such data, Sir Isaac Newton deter- mined the peri(xi when l^l^l^ the philosopher flourished, particu- larly from the famous eci/p$e which be predicted, and which hap- pened just as the two armies under AlgaUes^ king of Lydia, and Cyaxares the Mede were -engaged ; and which has oeen calculated to have happened in the 4th year of the 43d Ohinpiad, or is the year before Christ 603. On similar grounds Dr. Halley, a cele- brated astronomer of the last century, determined the very day and hour of the landing of Jlilius Cesar in Britam, merely from the tircumstances stated in the "Commentaries" of that * illustrious general. ^ Astronomy has likewise lent its aid to the PROPAGATION OF RELIGION, and the conversion of tne heathen world. For, without the light derived from this celestial science, oceans would never have been traversed, nor the continents and islands explored where benighted nations reside, and, consequently, no messengers of Peace could have been despatched to teach them " the knowledge of salvation, and to guide their steps in the way of peace." But, with the direction afforded by the heavenly orbs and the raapjnetic needle, thousands of Christian missionaries, along with millions of bibles, may now be transported to the most distant continents and islands of the ocean, to establish among them the " Law and Testimony" of the Most High — to illume the darkness and counteract the moral abor^ina- tions and idolatries of the Pagan world. If the predictions o* an- cient prophets are to be fulfilled^ if the glory of Jehovah is to cover V^^e earth ; if " the isles afar off,'^ that have not yet heard of the fame ^^w'^he Redeemer, nor seen his glory, are to be visited with tlie *^ Day-spring from on high," and enrolled among the citizens of Zion ; ii the world is to be regenerated, and Righteousness and Praise to spring forth before all nations — those grand events will be accomplished partly through the influence and direction of those celestial luminaridfe which ar^ placed in the firmament to be for signs, and for seasons, and fjrjdays and years. The light reflected from the material heavens willTlend its aid in illuminating the minds of the benighted tribes of mankind, till they be prepared for being transported into those celesti«t1^mansions wheie knowledge shall be perfected, and Sovereign A)ower triumphant. It will be likewise irom aid derived from the Hffayenly orbs that tht desolate wastes of the globe in every region .-viM be cultivated and replenbhed with inhabitants. For the Almighty " created not the earth in vain, bu formed it to be inhabited ;" and Uspurpose in this respect must ul iimately be accomplished: and the process of peopling and cultiva- lioD is now going forward 'n i«''cw Holland, Van Dicmen^$ Lanu. INTRODDCTIO?!. jyjj Afnca, the Wescern States of America, and other r^on& #hero sterility and desolation have prevailed since the universal Delnge. But how could colonies of men be transported from civilized na* tions to those distant regions miless by the guidance of celestial lu- minaries, and by the aid of those arts which are founded on the ob- servations of astronomy 1 So that this science exerts an extensive and beneficial influence over the most important aifairs of mankind. In short, astronomy, by unfolding to us the causes of certain ce- lestial phenomena, has tended to DISSIPATE SUPERSTITIOUS NOTIONS and vain alarms. In former ages the approach of a blazing comet, or a total eclipse of the sun or moon, were regarded with universa! g^earth ; if " the isles afar off,'^ that have not yet heard of the fame ^^Snthe Redeemer, nor seen his glory, are to be visited with the *'** Day-spring from on high," and enrolled among the citizens of Zion ; if the world is to be regenerated, and Righteousness and Praise to spring forth before all nations — those grand events will be accomplished partly through the influence and direction of those celestial luminari^ which ar^ placed in the firmament to be for signs, and for seasons, and fdridays and years. The light reflected from the material heavens wfUaend its aid in illuminating the minds of the benighted tribes of mankind, till they be prepared for being transported into those celesti«t1^mansions wheie knowledge shall be perfected, and Sovereign^wer triumphant. It will be likewise irom aid derived from the ll|fatrenly orbs that tht desolate wastes of the globe in every region^^yM be cultivated and replenu?hed with inhabitants. For the Almighty " created not the earth in vain, bu formed it to be inhabited ;" and. his purpose in this respect must ul iimately be accomplished : and the process of peopling and cultiva- lioD is now going forward '3 y«w Holland, Van Dicmen*;: Lanu. INTRODDCTIO^I. xiU Africa, the Wescem States* of America, and other regions #hero sterility and desolation have prevailed since the universal Delnge. But how could colonies of men be transported from civilized na* tions to those distant regions unless by the guidance of celestial la- minaries, and by the aid of those arts which are founded on the ob- servations of astronomy 1 So that this science exerts an extensive and beneficial influence over the most important aifairs of mankind. Id short, astronomy, by unfolding to us the causes of certain ce- lestial phenomena, has tended to DISSIPATE SUPERSTITIOUS NOTIONS and vain alarms. In former ages the approach of a blazing comet, or a total eclipse of the sun or moon, were regarded with uniyersal 'Consternation as prognostics of impending calamities, and as har- bino^ers of Divine vengeance. And even in the present day, such notions prevail among most of those nations and tribes that are un- acquainted with astronomical science. During the darkness occa- sioned by a solar eclipse, the lower orders of Turkey have been seen assembling in clusters m the streets, ^zing wildly at the sun, running about in wild distraction, and firmg volleys of muskets at ihe sun to frighten away the monster by which tney supposed it was about to be devoured. The Moorish song of death, or the howl they make for the dead, has been heard, on such occasions, resounding from the mountains and the vales, while the women brought into the streets all the brass pans, and vessels, and iron utensils they could collect, and striking them with all their force, and uttering dreadful screams, occasioned a horrid noise that was heard for miles around. But astronomy has put to flight such ter- rific phantoms and groundless alarms, by unfolding to us the true causes of all such phenomena, and showing us that they happen in exact conformity with those invariable laws by which the Almighty conducts the machine of the universe — ^that eclipses are merely the efliects of the shadow of one opaqiie globe iSUing upon another, and that comets are bodies which move in regular, but long elliptical orbits — which appear and disappear in stated periods of tinje, and are destined to suh>erve some grand and beneficent designs in thenys^.- tem to which they belong. So that we may now contemplate all such celestial phenomena, not only with composure and tranquillity, but with exultation and delight. In short, astronomy has under- mined the absurd and fallacious notions by which the professors of Judicial Astrology have attempted to impose on the credulity of mankind, under pretence of disclosing the designs of FaiCy and the events of futurity. It shows us, that the stars are nlaced at im- measurable distances from our terrestrial sphere — that they can have no influence upon the earth, but what arises from the law of universal gravitation — ^that the gi^at end for which they were crea- ted was to diffuse light, and to perform other important services in regions infinitely distinct from the sphere we occupy — that the pla- nets are bodies of different sizes, aflcl somewhat similar to the globe on which we live—that all their aspects and conjunctions a^e the result of physical laws which are regular and immutable — and Uiat no data can be »s<»ertain*»d on which it can be proved that the/ y{y INTRODIXJTION. exert a moral mflitence on the temperaments and destinies o^'tut^Si except in so far as thej^ tend to raise our affections to their Al- mighty Author, and excite us to confide m his care, and to contem- plate the effects of his wisdom and omnipotence. The heavenss are set before us, not as the " Book of Fate,^* in which we may piy into the secrets of our future destiny, which would only serve to destroy activity, and increase the pressure of our present afflictions — but as the " book of God," in wnich we may read his wondrous works, contemplate the glory of his eternal empire, and be excited to extend our views to those expansive scenes of endless felicjity which await the faithful in the realms above. . Independently of the considerations above stated, the study of as- tronomy is attended with many advantages in a moral, intellectiial, %nd religious point of view. I. Tms department of science unfolds to us Ihe most striking dis- plays of the perfections of the Deity, — ^particularly the grandeur of his Omnipotence. His Wisdom is conspicuously displayed in tlie general arrangement of the heavenly oife, particularly in reference to the globes which compose the solar sjrstem — in placing near the centre of this system that immense luminary the Sun, from whence light and heat might be distributed, in due proportion, to all the worlds thi roll around it — in nicely proportionating the motions and distaoces of all the planets primary and secondary — in uniting them in one harmonious system, by one grand universal law which prevents them from flying off in wild confusion through the infini> ty of space-^in t^ e constancy and regularity of their motions, no one interfering with another, or deviating from the course pre- scribed^in the exactness with which they run their destined rounds, finishing their circuits with so much accuracy as not to de- viate from their periods of revolution, the hundredth part of a mi- nute in a thousand years — in the spherical figures given to all those mighty orbs, and the- diurnal motions impressed upon them, by which a due proportion of light and heat is diffused over every part of their surface. The Benevolence of the Deity shines no less con- spicuous in those upper regions, in ordering all the movements an-A airangements of the celestial globes so as to act in subserviency to the comfort and happiness of sentient and intelligent beings. For, the wisdom of God is never employed in devising means wi'iiout an end ; and the grand end of all his arrangements, in so far as our views extendi is the communication of happiness ; and it would Jbe inconsistent with the wisdom and other perfections of Gkid not^to admit, that the same end is kept in view tn every part of his dcmin^ ioTis^ however far removed from the sphere of our contemplation. The heavens, therefore, must be considered as presenting a bouml- less scene of Di'ine benevolence. For they untold to view a count- less number of magnificent globes, calculated to be the habitations of various orders of beings, and which are, doubtless, destined to be the abodes of intellectual life. For the character of the Deity would be impeached, and his wisdom virtuidly denied, were we to sup- pose him to arrange and establish a magnificent series of mentis without an end corresponding, in utility and dig nil y, to the gran- ersed with a ^reat variety of mythological, historical and philosophical informs^ tion, calculated to amuse and instruct the general reader, and to arrest the attention of the young. The descriptions of the bodies connected with the solar system, are both popular and scientific, containing a lucid exhibition of the facts wnich have been ascer- tained respecting them, and a rational explanation of the phenomena connected with their various aspects and motions. The Celestial Atlas which accompanies the work is varied, comprehensive, and judiciously constructed, and forms the most complete set of planis- pheres, for the purpose of teaching, which has nitherto been pub- lished. It consists of four maps about fourteen inches square, de- .ineated on the same principles as geographical projections, exhi- oiting the stars that pa^s near the meridian at a certam hour, along with the circumjacent constellations for every month, and for every day of the year. Besides these there are two circumpolar maps of the northern and souihern hemispheres of the heavens, and a pla- nisphere on the principle of Mercator's projection, which exhibits at one view the sphere of the heavens, and the relative positions of the different constellations and principal stars. With the assistance of these maps, which in a great measure supersede the use of a celestial globe, an intelligent teacher may, at certain intervals in the course of a year, render his pupils familiar with most of the visible stars in the heavens ; and they will make a deeper impres- sion on their minds when taught in this way, than by the use of a globe. This work, on the whole, indicates great industry and re- search on the part of the author, and a familiar acquaintance with the various departments of the science of the heavens. He has de- rived his materials from the most valuable and modern works of science, and has introduced not a few illustrations and calculations of his own, which tend to enhance the general utility of the work. The moral and religious reflections which the objects of this science naturally suggest, have not been overlooked, and, I trust, will have a tendency to raise the minds of the young tc ^hat Almighty Bein^;: whose power, wisdom, and superintending ^*' ^^iV^u'^.c 8»*e !^ "stn- kingly displayed throughout the regions o?0i * *» ir^ni m*. PRELIMINARY CHAPTER. In entering upon this study, the phenomena of the heayens. a 3 mey appear m a clear evening, are the first objects that demand our attention. Our first step is to learn the names and positions of the heavenly bodies, so that we can identify, and distinguish them from each other. In this manner, they were observed and studied ages before books were written, and it was only after many, careful and repeated observations, that systems and theories of Astronomy were formed. To the visible heavens, then, the attention of the pupil should be nrst directed, for it is only when he shall have become in some measure, familiar with them, that he will be able to locate his Astronomical knowledge, or fully comprehend the terms of the science. For the sake of convenient reference, the heavens were early divided into constellations, and particular names assign- ed to the constellations and to the stars which they contain. A constellation may be defined to be a cluster or group of stars embraced in the outline of some figure. These figures are in mauy cases, creations of the imagination, but in others, the stars are in reality so arranged as to form figures which have some resemblance to the objects whose names have been as signed to them. These divisions of the celestial sphere, bear a striking analogy to the civil divisions of the globe. Tlie constellations answer to states and kingdoms, the most brilliant clasters to towas and cities, and the number of stars in each, tc their respective population. The pupil can trace the boundaries of any constel- lation, and nanie all its stars, one by one, as readily as he can trace the buuntbu ries of a state, or name the towns and cities from a map of New England. In this sense, there may be truly said to be a Geography of the Heavens. The stars are considered as forming, with reference to their magnitudes, six classes ; the brightest being called stars ot the first magnitude, the next brightest, stars of the second magnitude, and so on to the sixth class, which consists of the smallest stars visible to the naked eye. In order to be able Why, In entering upon the study of Astronomy, should the attention of the pupil bo first directed to the visible heavens? Why were the heavens early divided into con- stellations, and names assigned to the constellations and the stars? What is a con* stellation? Do these figures really exist in the skies? In what sense tnay tftere triM be said to he a Qeogramf of the Heavene ? How many classes are the stars considered as formlDg with teference to their mn^ilttide . ' 26 PRELOnNARY CHAPTEB to designate, with precision their situations, imaginary circles hare been considered as drawn in the heayens, most of which correspond to and are in the same plane with similar circles, supposed, for similar purposes, to be drawn on the surface oi the Earth. In order to facilitate the study, of it, artificial representations of the heavens, similar to those of the surface of the Eartli, have fapen made. Thus, a Celestial Atlas, composed of se- veral maps, accompanies this work. Before, however, pro- ceeding to explain its use^ it is necessary to make the pupil acquainted with the imaginary circles alluded to above. Circles or the Sphere. — The Aaria of the Earth is an imaginary line, passing through its centre, north and south, about which its diumsil revolution is performed. The Poles of the Earth are the extremities of its axis. The Axis of the Heavens is the axis of the Earth pro- duced both ways to the concave surface of the heavens. The Poles of the Heavens are the extremities of their axis. The Equator of the Earth is an imaginary great circle passing round the Earth, east and west^ everywhere equally distant from the poles, and dividing it into northern and southern hemispheres. The EqucUor of the Heavens, or Equinoctial, is the great circle formed on the concave surface of the heavens, by pro- ducing the plane of the Earth's equator. A plane ia that which has surface but not thickiiesa. The plane of a circle !« ^tfiat imaginary superficies which is bounded by the circle. The Rational Horizon is; an imaginary great circle, whose plane, passing through the centre of the Earth, divides the neavens into two hemispheres, of which the upper one is called the visible hemisphere, and the lower one, the invisi- ble hemisphere. It is the plane of this circle which deter- mines the rising and setting of the heavenly bodies. The Sensible or Apparent Horizon, is the circle which terminates our view, where the Earth and sky appear to meet. To a person standing on a plain, this circle is but a few miles in diameter. It the eye be elevnted five feet, the radius of the sensible horizon will be less than two miles and three quarters ; if the eye be elevated six feet, it will be just three miles. The observer being always in the centre of the sensible horizon, it wiU move as he moves, and enlarge or contract, as his station is elevated or depress* ed. What expedient has been devised for designating, with precision, the situations of the heavenly bodies ? What Is the axi« of the Barlh } What are the poles of tlie Earth ? What is the axis of the heavens ; What are the poles of the heavens? What is the •quator of the Earth 1 What is the equator of the heavens or the eqtiinoctia] ? What Ut mplanel What ia thepkme qfaetrcU? What is the rattotaal horizon? What is the sensible or apparent horizon? What is the diameter of tMe circle to a person stand' Hisrqna plain 7^ What toiU its radius be if the epe be eXewuedJlve feet 1 Ifitbe »•> vired sticfeet 7 On what does the plaas (^ita centrs and its cirem^rence depends rRBLI&ilNAUY CHAPTEIU 27 The Poles of the Horizon are two points, of which the one IS directly o7er head, and is called the Zenith ; the other is directly under foot, and is called the Nadir, Vertical Circles are circles drawn throu^^h the Zenith and Nadir of any place, cutting the horizon at right angles. The Prime Vertical is that which passes through the easi and west points of the horizon. " The Ecliptic is the great circle which the Sun appesurs to describe annually among the stars. It crosses the Equinoc- tial, a little obliquely, in two opposite points which are called the Equinoxes. Tne Sun rises in one of these points on the 21st of March ; this point is called the Vernal Equinox. It sets in the opposite point on the 23d of September ; this point is called the AtUumnal Equinox. One hau of the ecliptic lies on the north side of the Equinoctial, the other half on the south side, making an angle with it of 23^^. This angle is called the cbliquity of the Ecliptic. The axis of the Eclip- tic makes the same angle^«with the axis of the heavens ; so that the poles of each are 23^° apart. This angle is prrpetually decreasing. At Oie commencement of the Christian era, it was about 230 45'. At the beginning of 1836. it was only 23° 27' 38 ", show- ing an annoal diminution of about half a second, or 45'^70 in a hundred years. A tiuie will arrive, however, when this angle, having reached its minimum, will again increase in the same ratio that it had before diminished, and thus it will continue to oscillate at long periods, between certain limits, wliich are said to be comprised within the space of 20^ 42^. The ecliptic, like every other circle, contams 360°, and it is divided into 12 equal arcs of 30^ each, called signs, which the ancients distinguished by particular names. This division commences at the vernal equinox^ and is continued east- wardly round to the same point again, in the following order : Aries, Taurusy Gemini, Cancer, Leo, Virgo, Libra, Scor- pao, Sagittarius, Capricomus, Aquarius, Pisces, The Sun. commencing at the first degree of Anes, about the 21st oi March, passes, at a mean rate, through one sign every month. The Zddiac is a zone or girdle, about 16 degrees in breadth, extending quite round the heavens^ and including all the heavenly bodies within 8^ on each side of the ecliptic. It in- cludes, also, the orbits of all the planets, except some of the asteroids, since they are never seen beyond 8° either north or south of the ecliptic. Parallels of Latitude are small circles imagined to be What axe tht poles of the borizqai What are vertical circles i What Is the prima vertical ? What is the ecliptic I what are the equinoxes 1 The vernal equinox ? Tho ■iitiannal equinox 7 How is the ecliptic situated with respect to the equinoctial i What Is the obliquity of the eclipUc 7 Describe the manner in which thi» emgleyariea. Oe- jcrfbe the division of the ecllpUc Into signs. How much, at a m^n ratftj^oes the Sim «lvance In the ecUptlc every month? What Is the aodiac? What a» parallels of Mtkude? 90 rRELlMIMARY GIlAP^fS. drawn ou the Eafth's surface, north and south of the equator, and parallel to it. Parallels of Declination are small circles, imagined to be drawn on the concave surface of the hf^arens, north and south of the equinoctial, and parallel to it ; or they may be consid- ered as circles formed by producing the parallels of latitude to the heavens. The Tropic of Cancer is a small circle, whkh lies 23^*= north of the equinoctial, and parallel to it. Toe Tropic oj Cajyricorn is a small circle, which lies 23^ south of th* equinoctial, and parallel to it. On the celestial sphere, these two circles mark the limits of the Sun's farthest declination north and south. On the terrestial sphere, they divide the torrid, from the two temperate zones. That doint in the ecliptic which touches the tropic of Cancer, is called the Surnr- mer Solstice ; and that point in the ecliptic which touches the tropic of Capricorn, is called the Winter Solstice, l^c distance of these two points from the equinoctial, is always equal to the obliquity of the ecliptic, whicli, in round numbers, is 2ic° ; but as we nave seen the obliquity of tiie ecliptic is continually changing ; therefore the position of tho tropics must niake a correspondent change. The Colures are two great circles which pass through the poles of the heavens, dividing the ecliptic into four equal parts, and mark the seasons of the year. One of them passes through the equinoxes at Aries and Libra, and is thence called the Equinoctial Colure; the other passes through the solstitial points or the points of the Sun's greatest declination north and south, and is thence called the Solstitial Colure. The Sun is in the equinoctial points the 21 st of March and the 23d of Septeiu ber. lie is in the solstitial points the 23d of June and the 22d of December. The Polar Circles are two small circles, each about 66Jo from the equator, being always at the same distance from the poles that the tropics are from the equator. The northern is called the Arctic circle, and the southern "iho Antarctic circle. Mendians are imaginary great circles drawn through the poles of the world, cutting the equator and the equinoctial aC oght angles. Every place on the Earth, and every corresponding point in the heavens, i« considered as having a meridian passing througn it ; alUiough astronomers apply What are parallels cf declination ? What Is the tropic of cancer? What is the trepic ?I^*P5i'''^"*' What is the summer solstice? What is the winter solstice? What U tMir dU/tancefrom the equator, compared with the obliquity ^ the ecttptie? Is this wv.^ff f'^lf^^K^/,^ .*^^?* ' ^^^^ ^^ ^^^ colures ? What Is the equinoctial colure? noiiSsf n« ^w^il^c*'',"'^' , On what .lavs of the ye^ir Is the sun In the equinoctial wte?nnm« J^th/v^ !»?® ^". ^^^ .^^^^,Vi»' »^'n'=* ' ^^^ «re »he polar circles ? By SrA,^T?r«fIl,^'^*^^'"""?S^*'^«'^'' What are meri.lians? Row many meridian* vrt then i iioto many, do a»trbnmnera apply to the heaven* j ^ v*cr*a*anm rilELIMINAaY CHAPTER. t^ !»ni !^ to the heavens, thas dtrlding the whole concsre Bur&ce into 21 section^ eacli 15° in width. These meridians mark Uie space which the hebTenly bodies appear to describe, every hour, for the 21 hoars of the day. They are thence •ometmies denominated Hour Circlet, In measaring distances and determining positions on the Earth, the equator, and some fixed meridian, as that of Greenwich, contain the primary starting points ; in the heavens, these points are in the ecUptic, the equmoctial, and that ireat meridian which passes through the first point of Aries, called the equinoc- tial coiure. LcUitvde onrthe Earthy is distance north or south of the eqttator^ and is measured on a meridian. LtcUitnde in the Heaveng, is distance north or south of the ecliptic^ and at right angres with it Juongitude on the Earthy is distance either east or west from some, fixed meridian, measured on the equaior. Longitude in the Heavens^ is distance east from the first point of Aries, measured on the ecliptic, i Declination is the distance of a heavenly hody either north or south of the equinoctial, measured on a meridian. Right Ascension hs the distance of a heavenly body east firom the first point of Ar^es, measured on the equmoctial. It is mere convenient to describe the situation of the heavenly bodies by the^ declination and right ascension, than by their latitude and longitude, smce the former correspond to terrestrial latitude and longitude. Latitude and declination may extend 90^ and no more. Terrestrial longitude may extend 180*=* cither east or west ; but celestial longitude and right ascen- sion, being reckoned in only one direction, extend entirely round the circle, or 360®. In consequence of the Earth's motion eastward m its orbit, the stars seem to have a motion westward, besides their apparent diurnal motion caused by the Earth's revolution on its axis ; so that they rise and set sooner every succeeding day b)r about four minutes, than they did on the preceding. This is called their daily acceleration. It amounts to just two hours a month. ExAMPLB.— Those stars and constellations which do not rise until 10 o'clock this evening, will, at the same hour, one month hence, be 30^ above the horizon ; and, for the same reason, those stars which we see directly over head this evening, will at the same hour, three montlis hence, be seen settinsr in the west ; having in this time, performed one fourth of their ai^parent annual revo- lution. The following table of sidereal revohttiona, shows the difference between solar and sidereal time. The first column contains the numbers of complete revolu- tions of the stars, or of the Earth's rotation on its axis ; the second exhibits the Into how many §ection», do these meridians divide the concave surface cUs 1 In metisuring distances on the Earth, what circles contain the primary startifig foittts 7 Where are these points in measuring distances in the heavens 7 What Is la- Utode on the Earth? What is latitude in the heavens 1 What Is longitude on the Earth} What Is longitude in the heavens? What is declination 1 What Is rlfht ascension? H^y is it more convenient to describe the situation qf the heavenly bodies by their do- eUnation and right ascension, than by tfieir tatitttde and longitude 7 Bowmanyde- grees may latitude and declination eaetend7 How many terreurial lottgitude7 Bmm many eele»tiallongUude7 Whatlsmeantby the daily acceloiation of the stars? T9 sow many minutes does It amount? Dhtstrate this suiifcet vfim an eMmswa 3* «0 r&£X.IMINAaY CUaPTEII. tiuiei In which these revolutions are mode ; and the third, shows bow vanuM the Stan gain on the Bun every da^— that Is, how much sooner they rise and como to the meridian every succeedmg day, tiian they did on the prececfing I Revolutions Times In which Revohitlons 1 of the Stan. are made. daj-8. bo. min. sec I 23 66 4 s 1 23 52 8 8 2 23 48 12 4 8 23 44 16 6 4 93 40 20 6 6 23 86 24 7 < 23 89 88 8 T 23 98 88 9 8 83 94 86 iO 9 93 20 41 11 10 23 16 45 18 11 23 12 49 ts 12 83 8 63 14 13 23 4 67 15 14 23 1 1 18 16 29 67 3 IT 16 22 53 9 18 17 22 40 13 19 18 22 45 17 90 19 22 41 82 91 80 22 87 96 92 91 29 83 SO 93 22 82 29 84 94 93 22 85 86 95 21 92 91 42 96 25 29 17 46 97 26 28 13 50 98 27 22 9 64 90 98 99 S 68 80 29 22 9 3 40 89 21 22 44 £0 49 20 43 25 100 . w 17 26 50 900 199 10 53 40 300 299 4 20 80 360 8S9 24 88 865 864 4 66 866 865 1 Daily acceleration of tbft Stars. h. mln. sea 8 66 7 51 11 47 15 43 19 88 23 85 27 81 31 87 85 98 88 19 43 14 . 47 10 61 6 55 9 68 58 8 54 6 60 10 48 14 42 18 88 22 83 96 99 SO 95 84 21 88 17 48 18 46 9 50 6 54 1 57 67 » 2 87 16 8 16 85 6 83 10 IS 6 9 19 88 99 23 as 83 23 65 8 23 69 Ou this account, we have not always the same constelia tions visible to us throughout the year. While some, that were not visible before,. are successively rising to view in the east, and ascending to the meridian, others smk beneath the western horizon, and are seen no more, until, having passed through the lower hemisphere, they again reappear in the east. It is easy to convert right ascension into time, or time into right ascension: for if a heavenly Irady is one hour in passing over 16°, it will be one fifteenth or an hour, or 4 mmutes, in passing over 1°. If the first point of Aries be on the meridian at 12 o'clock, the next hour line, which is 15^ E. of it, will come to the meridian at 1 o'clock ; the second hoot line at 2 o'clock ; th« third at 8, &c. Of any two bodies whose right ascensiona are given, that one will pass the meridian^r*! which has the least right aseeBsion. The first map of the atlas represents, upon a large scale % general view of the solar system. This will be more fully described in the Second Fart of the Work. Do we • iSSliSl ^^'^t^^^mmc^S^^^"""'^ fif converting Hgm f » t rUEUMfNAIIY CIIAPTfilt. 91 f The next six maps represent diiTerent sections of the coneava surface of the heavens. The first of these exhibits the principal constellations visible to us in October, November and Decem- ber ; the second, those visible in January, February and March ; the third, those visible in April, May and June; and the fourth, those visible in July, August and September; with the exception, however, of the constellations which lie be- yond the 50th degree of north and south declination, of which, mdeed, those around the North Pole are cUways^ and those around the South Pole, never^ visible to us. T hese constellations are represented on the sixth and seventh maps, called clrcumpolar maps, which are an exact continu- ation of the ethers, and if joined to them at their correspond- ing degrees of right ascension and declination, they mi^t be considered as constituting one map. The scale on which adl the above-m8ntioned maps are drawn is that of a 16 inch globe. The lines drawn on the maps have been already de- fined ; and their use, being nearly the same with those in Gec^raphy, will be readily understood. Those which are drawn from right to left, on each side of the equinoctial and parallel to it, are called Parallels of DeclincUion. Those which are drawn up and down through the maps, at intervals of 15^, are called Meridians of Right Ascension^ or Hour Circles. The scale at the top and bottom of the first four maps, and in the circumference of the circumpolar maps, in- dicates the daily progress of the stars in right ascension, and shows on what day of the month any star will be on the me ridian at 9 o'clock in the evening. The consteDation called the Great Bear is aa exception to this mte ; in this constellation the principal stars are marked in the order of their right ascension. That point of projection for the maps which would exhibit each successiTO Dortiou of the heavens directly over head at 9 o'cloclc in the evening, was chosen, because in simimor at an earlier hour the twilight would bedim our observation of the stars, and at other seasons of the year it is easier to look up to stars ttiat want an hour of their meridian altitude than to those which are directly over head. It will be readily seen that the stars are so represented on the nu^s as to show their relative mamitudes. The method Invented by Bayer, of desigpatiag them by Che letters of the Oreek and Roman alphabets, is adoptea Thus in each con- steilation the stars are marked alpha, beta, &c., and should the letters of tha Greek al^phabet be exhausted, those of the Roman are employed. Some of tlie iitars have also proper names. . The first four maps of the heavens are so constructed that the — ■ — — — — — -^— ^. For what months does the first map represent the heavens 1 For what months doQS Che second map represent the heavens? The third? The fourth? What constellations aie represented on the sixth and seventh maps ? In what manner must these six maps oe arranged to fonn one compete map of the heavens ? On what scale axe these maps Irawn? Wh^ is the use of the scale at the top and bottom of the firstfoormM^. and hatbecircurafexenceofthecixoumpolarmaps? Why umu tjuu poUU qf prgftmonj^ head at 9 tfelock in the evening, choten 7 What ia the nuthai hjt «*/ Gamma A 6 Delta 5 * E « Epsilon e short Z i Zeta z B If Eta elon; e e Theta th I I ' Iota i K « Kappa k A X LamDda M a Ma m N • r Nu n 3 { Xi X O • OmieroD o short n » Pi p P p Rho r S ( 8igma a T T Tau t Y ^ V Upsilon u 4^ ^ Phi ph X X Chi ch ^' ^ Psi ps Q 6) Omega o long In 160B, John Bayer, of Augsburg, in Germany, published «■ complete Atlas of an the constellations, with the useful invention of denotmg t he stars m every Vhat is the only role of selecUon? What Is the stertto* point ^osanflw this wort What advantages has ihia rocrl lian as a atarUng pomt> 34 ^RBLIMINARY CHAPTER. CMiiiteltotkiB by the totten of the Ore^k and Roman Alphabeta ; asslgnhig tL« Greek letter a to the principal stars in each eonatellation, /S to the second in magnitiide, y to the third, and so on ; and when the Greek alphabet was ex- bausteti^ Uie notation was carried on with the Roman letters, a^h^t^ Ac. That the menionr might not be perplexed with a multitude of names, this convenient methodof aes^nating the stars lias been adopted bv all succeeding astronomers, who have fitfther enlarged it by the Arabic notauon, 1, 2^ 3^ Ac whenever the > in the constellations outnumbered l>oth alphabets. nrCREABE OF HIDKRRAT. TIME IN MEAN SOLAR HOURd, Ac Horn. 1 £ 3 4 6 6 7 6 9 10 11 12 13 14 16 16 17 18 19 90 21 22 23 24 Increase. m. 3 sec. 9.867 19.713 29.669 39.426 49.282 69.139 8.996 1&862 28.708 3a666 48.421 68.278 &134 17.991 27.847 37.704 47.660 67.417 7.273 17.130 26.966 86.842 46.099 66.666 Daily acceleration ofa star in passing the meridian, ID. see. 8 66^9086 Incr. Min. Incr. Bee. Incr. Bee. MUl 9CC* sec. sec. 1 0.164 81 6.093 1 aous 31 2 329 32 267 2 006 32 8 493 33 421 8 008 33 4 667 34 666 4 Oil 34 6 821 36 750 6 014 35 6 966 36 '914 6 016 36 7 1.150 87 6.078 7 019 37 8 314 38 242 8 022 38 9 479 39 407 9 025 39 10 643 40 671 10 027 40 11 807 41 736 11 030 41 12 971 42 600 12 083 42 13 2.136 43 7.064 13 036 43 14 300 44 228 14 038 44 16 464 45 3^2 15 Oil 45 16 628 46 667 16 044 46 17 793 47 721 17 047 47 18 . 967 48 886 18 M9 - 48 19 3.121 49 a060 19 062 49 20 286 60 214 20 055 60 21 460 61 378 21 058 61 22 614 62 642 22 060 62 23 778 63 707 23 063 63 24 943 64 871 24 066 64 26 4.107 66 9.035 25 069 65 26 271 66 199 26 071 56 27 436 67 364 27 074 57 28 600 68 623 28 077 63 29 764 69 698 29 079 5? 30 928 60 867 80 062 60 Incr. sec- 0.066 068 090 093 0U6 099 101 104 107 110 112 115 118 121 123 126 129 131 134 137 140 142 145 148 151 18S 156 159 162 164 \ TRB GEOGRAPHY OF THE HEAVENS, CHAPTER I. DfRECTIONS FOR TRACING THE CONSTELLATIONS WBICB ARl 0% THE MERIDIAN IN NOTEMBER. ANDROMEDA. If we look directly orer head at 10 o'clock, on the 10th 0< Noyember, we shall see the constellation celebrated in fable, by the name of Andromeda. It is represented on the map by the figure of a woman having her arms extended, and chamea by her wrists to a rock. It is bomided N. by Cassiopeia, K. by Perseus and the head of Medusa, and S. by the Triangles and the Northern Fish. It is situated between 20^^ and 50^ of N. declination. Its mean ris^ht ascension is nearly 15^ ; or one hour E. of the equinoctial colure. It consists of 66 visible stars, of which three are of the 2d magnitude, and two of the 3d; most of the rest are smalL The stars directly in the zenith, are too small to be seen hi the presence of the moon, but the bright star Almaack, of the 3d magnitude, in the left foot, may be seen 13<^ due K., and Merach, of the same magnitude, in the girdle, 7<^ south of the zenith. This star is then nearly on the meridian, and wit|i two others N. W. of it forms the girdle. The three stars forming the girdle are of the 2d, 3d. and 4th magnitude, situated in a row, 3^ and 4^ apart, ana are called Merach, Mil and Nu. About 2° from Nu at the northwestern extremity of the girdles, is a remarkable nebula of very minute stars, and the only one of the kmd which is ever visible to the naked eye. It resembles two cones of light, joined at their base, about ]<^ in length, and i^ in breadth. If we look directly over head at 10 o'clock on the loth of November, wtetcon«lelI»» Hon Shan we see? How Is it represented on the map? How is it bounded 7 Wiwt an lit rl|^t ascension and declination? How many visible stars has it? Describe the Clnflt ofADdromeda. Describe the appearance of a remarkable nebula which lies ai its m>rthwcstem extfamity. 39 PICTURE or THG HEAVENS. It a straig t line, connecting Almaack with Merach, be produced southwesterly, 8° farther, it will reach to Delia, a star of the 3d magnitude in the left breast. This star may be otherwise known by its forming a line, N. and S. with two smaller ones on either side of it ; or, by its constituting, with two others, a rery small triangle, S. of it. Nearly in a ime ^i^ith Almaack, Merach and Delta, out curving a little to the N. 7° farther, is a lone star of the 2d magnitude, in the head, called Alpheratz. This is the N. £. comer of the great " Square of Pegasus," to be hereafter de- scribed. It will be well to have the position of Alpheratz well fixed in the mind, bccaiii«o it 18 but one niinute west of the great equinoctial colure, or first meridian of the heavens, and forma nearly a right line with Algenib in the wing of Pegasua. 14^ B. of iL and with Beta m Cassiopeia, 30^ N. of it. If a line, connecting these three •tara, be produced, it will terminate in the pole. These three (guides, in connex- ion with the North Polar Star point out to astronomers the position of that great circle in the heavens from which the right ascension of all the heavenly bodicn is measured. History.— -The storv pf Andromeda, from which this constellation derives its name, is as follows: @he vras daughter of Cepheus, king of if^hiupia, by Cassio* Seia. She was pr^piised in marriage to Phineua, her uucle, u'hen 'Ne(»cune rowned the lcingd(un, and sent a sea monster to ravage the cnuuiry, to apiiease the resentment whiph his favourite Nymphs bore against Cassiopeia, because she had kxiasted herself fairer than Juno and tlie Nereides. The oracle of Ju> Piter Ammon was consulted, and nothing could pacify the anger of Neptune unless the beautiful Andromeda should be exposed to the sea monster. She was accordingly chained to a roctc for this purpose, near Joppa, (now Jal&, in Syria,) and at the moment the monster was gomg to devour her, Perseus, who was then returning through the ahr from the conquest of tlie Gorgons, suw Iter and waa captivated by her beauty. "Chained to a rock she stood ; yoimg Perseus stayed His rapid flight, to woo the beauteous maid." He promised to deliver her and destroy the monster if Cepheus would give her to him in marriage. Cepheus consented, and Perseus instantly changedthci sea monster into a rock, by showing him Medusa's head, which was still reeking in his hand. The enraged Pliincus opposed their nuptials and a violent battle ensued, in which he, alaoj was turned into a stone by the petrifying influence oi the Gorgon's head. The morals, maxims^ and historical events of the ancients, were usually com< mvnicated in fitble or allegory. The fable of Andromeda and the sea monster, might mean thiit she vras courted by some monster of a sea-captaiI^ who at- tempted to carry her away, but was prevented by another more gaUaut and sue* cessful rival. PISCES. TfiE Fishes,— This constellation is now the first in order, of the 12 constellations of the Zodiac, and is usually repre- sented by two fishes tied a considerable distance apart, at the extremities of a long undulating cord, or riband. It occupies Describe the magnitude and position of Delta. How may this star be otherwise ^nown ? lescribe the position and magnituJe of Alpheratz. "What position does this ft%«r occw»/ In the great square of Pegasus ? Why U U important to have the potiWrn %* .Ws^p- tMfi Jheed In the mind J What Is the present order of the Fishes amonc *9 vj^r" liUlons of the Zodiac i How i% it represented J Describe lu ouUbie and iqmSi ^ ^n ^ ens. nscES. 37 a laige tnangular gpace in the heavens, and its outline at first Is somewhat difficult to be traced. In eonseqaence of the annoal preceedon of the stan^ the wn^MltUun PtocM haa now come to occupy the ngn Aries ; each consteDaUon havinc advance^ one whole sign in the order of the Zodiac. The snn enters the sign Pisces^ white the earai enters that of Virm about the I9th of Febmans but he does not reach the constellation Pisces before the 6th of March. The Fisliec, therefor^ are now called the ** Leaders of the Celestial Hosts." — See Ariea. That loose assemblage of small stars directly south of Merach, in the constellation of Andromeda, constitutes the Northern Fish^ whose mean length is about 16<^, and breadth, 7°. Its mean right ascension is 15^, and its declination 25^ N. Consequently, it is on the meridian the 24th of Norem* ber ; and, from its breadth, is more than a week in passing over it. The Northern Fish and its riband, beginning at Merach, may, by a train of small stars, be traced, in a S. S. easterly direction, for a distance of 33^, until we come to the star El Rischa, of the 3d magnitude^ which is situated in the node, or flexure of the riband. This is the principal star in the constellation, and is situated 2^ N. of the equinoctial, and 53 minutes east of the meridian. Seven de^ees S. E. of E3 Rischa, passing hj three or four verf ciaal] we come to Mira, in the Whale, a star of about the 3d magnitude, and known as the '' Wonderful tttar of 1996." El Rischa may be otherwise identified br means of a remarlcable cluster of five stars in the form of a jsefWoj^ about lo^ B. of ^L — See Cetus. From El Rischa the riband or cord makes a sudden flexure, doubling back across the ecliptic, where we meet with three stars of the 4th and 5th magnitude situated in a row 3^ and A^ apart, marked on the map Zeta, Epsilon, Delta. From Delta the riband runs north and westerly alon^ the Zodiac, and terminates at Beta, a star of the 4th magnitude, 11<> S. of Markab in Pegasus. This part of the rjband including the Western Fish at the end of it, has a mean declination of 5^ N., and may be seen throughout the month of November, passing the meridian slowly to the W., near where the sun passes it on the 1st of April. Twelve degrees W. of this Fish, there are 4 small stars situated in the form of the letter Y. The two Fishes, and the cord between them, make two sides of a large triangle, 30° and 40° in length, the open part of which is towards the N. W. When the Northern Fish is on the ~What are the size and position of the Norttiem Fish ? When, and how long is it on the .-nerldianl How may it be tniced? What is the principal star in this constellation, and where is it situated J How for, and in what direction from Alpha, is Mira, in the Whalet By what peculiar appellation Is this star known ? What is the direction of the ribRndfrom Alpha? what stars do we meet with, where the riband doubles back across U»e eclip- tic ? What is the direction of this part of the riband from Delta, and where does »t>^ minate l What are its mean declination, and the time of its passing the meridian ? ^hat striking cluster is seen about laP W. of the Western Fish? ^hat geometrical flsurs may be conceived to be formed by the two Pishes and the rorl between them' wimm is the Western Fish when the Northern is on the meridian ? 4 38 PrCTURB of THE HEAVIINS. [:40 meridian, the Western is nearly 2 hoars past it. Tfds co. stellation is bounded N. by Andromeda, W. by Andromeu and Pegasus, S. by the Cascade, and £. by the Whale, tl « Ram and the Triangles. When, to enable the pupil to find any star, its direction firom another is girei . the latter is always understood to be uh the meridian. After a litUe experience with tlie maps, even though unaccompanied by dently this : that there is in the world a description of men whose mouth is sc "full of cursing and bitterness," derision and violence, that modest virtue is sometimes forced to disguise itseli; or flee from their presence. In the Hebrew Zodiac, Pisces is allotted to the escutcheon of Simeon. No sign appears to have been considered of more malignant influence than Places. The astrological calendar describes the emblems of tliis constellation as indicative of violence and death. Both the Syrians and I^yptians abstained firom eating fish, out of dread and abhorrence : and when the latter would re- present any thing as odious, or express hatred Dy hieroglyphics, they painted a fiah. In using a circumpolar map, fiuse the pole, and hold it up in your hands m ■uch a manner that the part which contains the name of the given month sliall be uppermost, and you will have a portraiture of the heavens as seen at that time. The constellations about the AntarcUc Pole are not visible in the United States ; those about the Arctic or northern pole, are always visible. CASSIOPEIA. Cassiopeia is represented on the celestial map, in regal state seated on a throne or chair, holding in her left hand Uie branch of a palm tree. Her head and body are seen in the Milky Way. Her foot rests upon the Arctic Circle, upon which her chair is placed. She is surrounded by the cliiei personages of her royal family. The king, her husband, is on her right hand — Perseus, her son-in-law, on her left — and Andromeda, her daughter, just above her. This constellation is situated 26^ N. of Andromeda, and midway between it and the North Polar Star. It may be Wbartsv) !lae bo«aia« « of this constellatlonT How Is the constellaUon Cassiopeia 'llffiP?^' '* ••"*•. ^ _ By whom Is the surrounded! Howls this conttsllatkm — ^ • "isr^MDt ^ feMMda aQ4 the pqlar starJ MikP VI. I CASdlOPKU, SO seen, from our latitude, at all hours of the night, and may be traced out at almost any season of the year. Its, mean deeU- natjon is 60^ N. and its right ascension I2<^. It is on our meridian the 22d of November, but does not sensibly change its position for several days ; for it should be remembered that the apparent motion of the stars becomes slower and slower, as they approximate the poles. Cassiopeia is a beautiful constellation^ containing 55 stars that are visible to the naked eye ; of which five are of the 3d magnitude, and so situated as to form, with one or two smaller ones, the figure of an inverted chair. « wide her stars Dispersed, nor shine with mutual aid improved; Nor dazzle, brilliant with contiguous flame : Their niunber fifty-fiTe." Caph, in the garland of the chair, is almost exactly in the equinoctial colure, 30^ N. of Alpheratz, with which, and the Polar Star, it forms a straight line. [^See note to Androme- da.'] Caph is therefore on the meridian the 10th of Novem- ber, and one hour past it on the 24th. It is the westernmost star of the bright cluster. Shedir*^ in the breast, is the up- permost star of the five bright ones, and is 5^ S. K. of Caph : the other three bright ones, foiming the chair, are easily dis- tii^uished, as they meet the eye at the first glance. There is an importance attached to the position of Caph that concerns the mariner and the surveyor. It is used, in connexion with observations on the Polar Star, for determi- ning the latitude of places, and for discovering the magnetic variation of the needle. It is generally supposed that the North Polar Star, so called, is the real immove • able pole of the heavens ; but this is a mistake. U is «o near the true pole that it has obtained the appellation^f the North Polar Star ; but it is, in reabty, more than a degree and a half distant from iL and revolves about the true ix>le eveiy 91 hours, in a circle whose radius is 1^ 2&\ It will consequently, in 21 hours, be twice on the meridian, once above^ and^Slce below the poUi; and twice at its greatest elongation E. and W. [Set NortA Polar Star.] ' The Polar Star not being exactly in tji^e N. pole of the heavens, but one degree and 35 minutes on that side of it which is towards Caph, the position of the latter becomes important as it always shows on which side of the true pole thepolar star is. Tnere is another important fact in relation to the position * Shedir. from El Seder, the Seder tre^; a name given to this constellation by UlughBeigfa. When may It be seen from this latitude? When is it on our meildiuti .How Isthe mtitlou of the stars aflfected as tbey approach the poles ? How many P'^nSP" f ^9* i? this amstcllation, and what U their appearance? Dcscritio »e sRuaUonof ^gu WhenisC^honthemeridtanl WhJt ff the lelaOve poslttcn of Shedir? wnyistfc* rgsitiOD of Caph bnportaiitt 40 PICTURE OF THE REAVEK8. NOV of this Star. It is equidistant from the pole, and exactly ep- posUe another remarkable star in the square of the Great Bear, on the other side of the pole. [SeeJUegrez,'] It also serres to mark a spot in the starry heavens, rendered memo- rable as being the place of a lost star. Two hundred and fifty years ago, a bright star shone 5° N. N. £. of Caph, where now is a dark void ! On the 8th of November, 1572, Tycho Brahe and Corne- lius Gemma saw a star in the constellation of Cassiopeia, which became, all at once, so brilliant, that it surpassed the splendour of the brightest planets, and might be seen even at noonday ! Graduafiy, this great brilliancy diminished, until the 15th of March, 1573, when, without moving from its place, it became utterly extinct. Its colour, during this time, exhibited all the phenomena of a prodigious flame — first it was of a dazzling white, then of a reddish yellow, and lastly of an ashy paleness, in which its light expired. It is impossible, says Mrs. Somerville, to imagine any thing more tremendous than a conflagration that could be visible at such a distance. It was seen for sixteen months. Some astronomers imacin^d that it would reappear again after 150 years; but it has never been discovered since. This phenomenon alarmed all the astronomers of the age, who beheld it; and many of them wrote dissertations con- cerning it. Rev. Professor Vince, one of the most learned and pious astronomers of the age, has this remark : — " The disappear- ance of some stars may be the destruction of that system al the time appointed by the Deity for the probation of its in- habitants ; and the appearance of new stars may be the for mation of new systems for new races of beings' then called into existence to adore the works of their Creator." Thus, we may conceive the Deity to have been employed from all eternity, and thus he may continae to be employed for endless ages ; forming new bj»- tems of beings to adore him ; and transplanting beings au-eady formed into hap* pier regions, who will continue to rise higher and higher in their enjo^ments^ and go on to contemplate system after system through the boimdless universe. La Placb says : — "As to those stars which suddenly shine forth with a very vivid light, and then immediately disappear, it is extremely probable that great conflagrations, produced by extraordinary causes, take place on their surface. This conjecture, continues he, is confirmed by their chauge of colour, which is analogous to that presented to us on the earth oy those bodies which are set on fire and then graaually extinguished." The late enunent Dr. Good also observes that->-World8 and systema of worlds What memorable spot does Caph serve to mark oati Descrlbe^the phenomenon of the lost star. What does Mrs. Somerville say of It} How long was it seen? Has any thing been discovered of it since 1 How did this phenomenon affeot the astroiUMnera of the age 7 What does Vince say of the disappearance of some stars, and the new a»- poaxance of othersi Repeat Ote MtenatUme ofUr. Good upon the eutiect of new afars €9f«rtfi^ and dieappearintr. I iii^i7" I > II • SSJmi »-jf*lg. ^^ mtf^ _ Map VI. 1 cspUEUfli. ii %« not only pefpetoadly ereating^ but also perpetually disappearing. It Is hi taiinordinary fact, that within the period of the last century, not less than (hif cen stars, in different constellations, seem to have totally i>eri8hed, and ten new •nvs to have been created. In many instances it is unquestionable, that the stars themselves, the supposed habitation of other kinds or orders of faiteUigent be- ingfa, together »nth tne different planets by which it is probable ther were sar< rounded, have utterly vanished, and the spots which they occupied in t* e he** vena, have become blanks ! What has be&llen other systems, will aasoredlT befadl our own. Of the time and ttie manner we know nothing birt Uie fret is incontrovertible ; it is foretold by revelation ; it is inscribed in the heavens ; k is felt through the earth. Such is the awAil and daily text ; what then ought tn be Uie comuienti The great and food Beza, falling in with the superstition of his age, attemMei to prove that this was a comet, or the same luminous appearance which conaac^ ed Che rajagi, or wise men of the East, into Palestine, at the birth of our flavkmr and that it now appeared to announce his second coming ! Abouf 6° N. W. of Caph, the telescope reveals to us a graad nebula of small stars, apparently compressed into one mass, or single blaze of light, with a great nmnber of loose stars surrounding it. HisTORT. — Cassiopeia was wife of Cepheus, lang of .£diiopia, knd mother of ▲&> dromeda. She was a queen of matohleas beauty, and seemed to be sensible of it ; for she even boasted herself fairer tlian Juno^ the sister of Jupiter, or the Nerei* des — a name given to the sea nymphs. This so provoked the ladies of the sea that tliey complained to Neptune of the insult, who sent a frightful monster to ravage her coast, as a punishment for her insolence. But the anger of Neptune and the jealousy of the nvmphs wera not thus appeased. They demanded, and it was finally ordained that Cassiopeia should chain her daognter Andromeda, whom she tenderly loved, to a desert rock on the beach, and leave her exposed to the liiry of this monster. She was thus left, and the monster ^preached ; but joaC as he was going to devour her, Perseus killed him. "The saviour youth the royal pair confess, And with heav'd hands, their daughter's bridegroom bless." Euaden*9 Ovid. CEPHEUS Cepheus is represented on the map as a king, in his royal robe, with a sceptre in his left hand, and a crown of stars upon his head. He stands in a commanding posture, with his left foot oyer the pole, and his sceptre extended towards Cassio- peia, as if for favour and defence of the queen. ■ "Cepheus illumes The neighbourinc heavens ; still iaithful to his queen, With thuty-five Mint luminaries mark'd." This constellation is about 25^ N. W. of Cassiopeia, near the 2d coil of Draco, and is on the meridian at 8 o'clock the 3d of November; but it will linger near it for many days. Like Cassiopeia, it may be seen at all hours of the nignt« when the sl^ is clear, for to us it never sets. By reference to the lines on the map, which all meet in the p<4e, it will be evi- 'jent that a star, near the pole, moves ovw a much Un space in one hour, than There Is a lemaxkable nebula In this consteUatkm ; describe its/'Uon^and ap- pettnmce. How is Cepheus represented 1 What is his postorsY IHk'^ • twr •••i ftellatlon situated? 4* > 48 PICTURE OF TH£ fiCAVENB. [KOf* 006 at the equinoctial i and ^enerallyi the naorer ttie pole, the num w er lint apnce, and the tlower the motion. The atara that are ao near the pole may be better deacribed by their polai' diftoneef than by their declinaticm. By polar diatance, ia mean^-the duUmet from the pcto ; and ia what the deelinatkm wanta of 90^. In this constellation there arc 35 stars risible to the naked eye *, of these, there glitters on the left shoulder, a star of the. 3d magnitude, called Alderaminy which with two others of the same brightness, 8^ and 12^ apart, form a sli^htl)[-curyed line towards the N. E. The last, whose letter name is Gam* ma. is in the right knee^ 19^ N. of Caph, in Cassiopeia. The middle one in me line, is Alphirk. in the girdle. This star is one third of the distance from Alderamin to the pole, and nearly in the same right line. It cannot be too well onderatood that the bearinga. or direction of one atar from another, aa given in this treatise, are strictly applicable only when the former one ia on, or near the meridian. The bearings given, in many casea, are not the leaat approximations to what appears to be their relative position ; and in some, if relied npon, will lead to errours. For example : — ^It is said, in the precediiv paragn^ph, that Gainma, tn Cepheus, bears 19° N. of Caph in Cassiopeia. Thia 18 true, when Caph is on the meridian, but at this very moment, while the author la wilting this line, Oamma appears to be 19° due west of Ca^h ; and ax montha hence, will a)^ear to be the same distance ecut of it. The reason is obvious ; the circle which Cepheus appears to describe about the pole, is teithin tliat ot Cassiopeia, and consequently when on the eaat side of the pole, will be leitkin, or between Cassiopeia and the pole— that la, teeat of Cassiopeia. And for the aame reason, when Cepheus fa on the west aide of the lYole, it ia htttceen that and Caasiopeia, or eaat of it. Let it also be remembered, that m speaking of the po/e, which we shall have frequent occasion to do, in the course of this work, the North Polar Star, or an imaginary point very near it, ia always meant ; and not as some will vagueiy ap> prehend, a point tn the horizon, directly N. of us. The true pole of the heavena la always elevated just as many degrees above our horizon, as we are north of the Equator. If we live in 43P N. latitude, the N. pole will be 42° above our horizon. (,See North Polar Star.) There are also two smaller stars about 9^^ E. of Alderamm and Alphirk, with which they form a square; Alderamin being the upper, and Alphirk the lower one* on the W. 8° apart. In the centre of this square there is a bright dot, or semi-visible star. The heo^ ™a9^ it ba known t What Is the mean polax dl^pa o( tUa cons^dlaUoaf How Ckr, and which way li Itftom the eqninoetfa. MAP n.J AHIE8. 43 n SOP. Now 338<^, measured fnnn tbe same point, will reach the aame poial aiEflJn, within 22° ; which is the difference between 360'' and 338°. Tlris mU. wiU tipfAy to any other cas^ UisTOBT.— Tliis consteliation immortalizes the name of the king of JEthiopta. The name of his queen was Cassiopeia. They were the parents of Andromeda, who was betrothed to Perseus. Cepheus was one of the Argonauts who accompanied JaEon on his jterilous expedition in quest of tbe golden fleece. Newton supposes titat it was owing to this circumstance that he was pbiced in the heavens ; and that not only this, but all the ancient constellations, relate to the Argonautic ez- Sedition, or to persons some way connected with it Thus, he observes that as lusKus. nne ot tbe Ar^nnauts, was the first Greek who made a celestial sphere, he wouia naturally dcbneate on it those figures which had some reference to the expedition. Accordingiv, we have on our clobes to this day, the Golden Rantf tlie ensign of the ehip in which Fhryxus fledto Colchis, the scene of the Axvo- nautic achievements. We have also the Butt with brazen hoofs, tamed by Ja> con ; the Twins, Castor and FoUux, two sailors, with their mother LedOf in the ibnii o^a Sftoariy and Argo, the ship itself; the wishful JDra^on Hydra, with the Cup of Medea, and a raven upon its carcass, as an emblem of death ; also Chi- ron, the Master of Jason, with his AUar, and Sacrifice; Hercules, the Argonaut, wltii his club, his dart, and vulture, with the dragon, crab and Uon which he dew ; and Orpheus, one of the company, with his harp. All these, says Newton, refer lo the Argonauts. Again ; we have Orion, the son of Neptnne, or, as some say. the grandson of Miuos. with his dogs, and hare, and rtfer, and scorpion. We nave the story of Perseus in the constellation of that name, as well as in Cassiopeia, Cepheus, An* dromeda and Cetus; that of Calisto and her son Areas, in Ursa Major ; that of Icarens and his daughter Erigone, in Bootes and Virgo. %Ursa Minor relates to one of the nurses ofJupiter ; Auriga, to Erichthonius -^^hiuchtu, to Pborbas^ Sagittarius, to Crolus, the son of one of thev Muses ; Capricorn, to Pan, ancP Aquarius to Ganymede. We have also Ariadne's crown, BellerOphon's J^bne, Neptune's dolphin^ Ganymede's eagU, Jupiter's goai with her kids, the asses of Bacchus, the Jishes of Venus and Cupid, with their parent, the southern fish. These, accormng to Beltoton, comprise the Grecian constellations mentioned by the poet Aratus ; and all relate, as Newton sopoose^^ remotely or immediately, to the Argonauts. It may be remarked, however, that while none of these figures refer to any transactions of a later date than the Argonautic expedition, yet the great disA- greement which appears in the mythological account of them, proves that their invention must have been of greater antiquity than that event, and that these constellations were received for some time among the Greeks, before their poeta referred to them in describing the particulars of that memorable exhibition. CHAPTER II. DIRECTIONS FOR TRACING THE CONSTELLATIONS WHICH ARE ON THE MERIDIAN IN DECEMBER. ARIES. Tf5j Ram. — Twenty-two centuries ago, as Hipparchus -n foniis us, this TTonstellation occupied Uie Jirst sign m the ecliptic, commencing at the venial equinox. But as the con- stellations gain about 5C on the equinox, at every revolution of the heavens, they have advanced in the ecliptic nearly 31'' beyond it, or more tnan a whole sign : so that the Fishes now • I ir "That was tbe position of Ailw in the ecliptic » csatuxtos ago) 14 PICTUUE or THE HEAVENS. {dCC occupy the same place in the Zodiac, that^Aries did, in the time of Ilipparchus ; while the constellcUion Aries is now in the sign Taurus, Taurus in Gremini, and Gemini in Cancer, and so on. Aries is therefore now the second constellation in tne Zodiac. It is situated next east of Pisces, and is midway between' the Triangles and the Fly on the N. and the head of Cetus on the S. It contains 66 stars, of which, one is of the 2d, one of the 3d, and two of the 4th magnitudes. "First, from the eaat, the Ram conducts the year ; Whom Ptolemy with ttoice nine sfars adorns, Of which two onlv claim the second rank ; The rest, when Cynthia fills the sign, are bat." It is readily distinguished by means of two bright stars in the head, about 4° apart, the brightest heinz the most north* easterly of the two. The first, which is of the 2d magnitude, situated in the right horn, is called Alpha Arietis, or simply Arietis ; the other, which is of the 3d magnitude, lying near the left horn, is called Sheratan, and may be known by an- other star of the 4th magnitude, in the ear, 1^° S. of it, called Mesarthim, which is the Jirst star in this constellation. Arietis and Sheratan, are one instance out of many, where stars of more than ordinary brightness are seen together in pairs^ as in the Twins, the Little Dog, d^c, the brightest star Dein^ commonly on the east. The position of Arietis affords important facilities to nau- tical science. Difficult to comprehend as it may be, to tiie unlearned, the skilful navigator who should be lost upon an unknown sea, or in the midst of the Pacific ocean, could, by measuring the distance between Arietis and the Moon, which often passes near it, determine at once not only the spot he was in, but his true course and distance to any known meri- dian or harbour on the earth. - Lying along the moon's path, there are- nine conspicuous stars that are used by nautical men for determining their lon- gitude at sea, thence called nautical stars. These stars ar^ Arietis, Aldebaran, Polhix, Regulus^ Spica Virginisy Aniares, )Altair, F^malhaut, and Markab. The true places of these stars, for everv day in the year, are given in thel<^ltn- tical Almanac, a valuable work publishca annually bythe English "BoanI of Ad- miralty," to guide mariners in navigating the seas. They are usually published ^vo or three years in advance, for the benefit of long voyages. That a man, says Sir John Herschel, by merely measuring the moon's appa. rent distance from a star, with a little portable instrument held in his hand, and What is its present jpostUottf How is it now situated with respect to the surround- ing constellatfonB? Wbatare the number and magnitude of Its stars? How is this constellaUon leaiUIy dlstingulshod 7 Describe the two bright stars in the head. For what purposes is the posiUon of some of the stars in Arietis important? How manj Stan ue used for detennining longitude at sea, and where are they situated ? By wtioK fBMna name a] ter into the upper vessel, and observing the rising of some star in the Zodiac, at the same time suffered the water to drop into one of the small vessels. And Stf 804HI as it was fuIL thev removed it, and set an empty one in its place. Jusc as each vessel was full, they took notice what star of the Zodiac rose at that timef and thus eenion. Of all the discoveries of the antiquanr among the relics of ancient Greece, the rains uf Palmyra, the gigantic pyramicu of Egypt, the temples of their gods, or the scpolchres of tlieir kings, scarcely one so aroused and riveted the curiosity of the learned, as did the cti«covery of Champollion the younger, which dcciphert :lte hieroglyphics of ancient Egypt. Tlie potency of this invaluable discovery has already been sigiially manifested in setthng a A>raiidable controversy between the champions of infidelity and those who maintain tlie llible account of the creation. It has been shown that the constellation PiaceSy since the days of Hipparchus, has come, by reason of the amiual precession, to occupy the same apparent place in the heavens that Aries did two thousand years ago. The Cluistian astronomer and tlie infidel are perfectly agreed as to the fact, and the anunmt of this yearly gain in the appa- lent motion of the stars. They botli l>elieve, and both can demonstrate, that the <^ fi^ed stars have gone forward in the Zodiac, about 50" of a decree in every revo* lution of the heaventi since the creation ; so that were the world to light upon any authentic inscription or record of past ages, which should give the true position or longitude of any pariicular star at that time, it would be easy to fix an unques- tionable •led 3 now long is (he Whale In passing tht msridiani 48 PICniSE OF THE BEATEIta. [dbo. tail comes to the meridian on the 10th of Novemher, and its Head leavea it on the 22d of December. This constellation contains 97 stais ; two of the 2d ma^ nitude, seTen of the 3d, and thirteen of the 4tb. The head ul' Cetus may be readily distinguished, about 20° S. K. of Aries, by means of five remarkable stars, 4° and 5° apart, and so situated aa to form h. regular pentagon. The brightest of these is Menkar, of the 3d magnitude, in the nose of the Whale. It occupies the S. E. angle of the figure. It is Si" N. of the equinoctial, and 15° S. of El Bischa in the bight o( the cord between the Two Fishes. It is directly 37° S. of Aleol, and nearly^ the same direction from the Ply. It makes an equilateral triangle with Arielis and the Pleiades, being distant from each about 23° 9. ;,and may otherwise be known by a. star of the 3d magnitudf in the mouth, 3° WNlf it, called Gamma, placed in the south miildle anglt of the it of the 4th magnitude, i° N. W. of Gamma, and these two constitute the 3. W. side of the pentagon in the head of the Whale, and the N. E. side of a similar oblong figure in the neck. Three degrees S. S. W. of Gamma, is another star of the 3d magnitude m the lower jaw, marked Delta, conslitutin^the £. side of the oblong pentagon ; and 6° 8. W. of this, IS a noted star in the neck of the Whale, called Mira, or the " wonderful star of 1596," which forms the S. E. side. This variable star was first noticed as such by Fa^cius, on the 13th of August,' 1596. It changes from a star of the 2d mag- nitude so as to became invisi^e once to 334 days, or about 7 times in 6 years, Herschel makes its period 331 days, 10 hours, and 19 minutes ; while Hevelius assures us that it once disappeared for 4 years ; so that its true period,, perhaps, has not bee a satisfactorily determined. The wliole nuinberoriunucertaiafdtabennabl«,aoi<>unUK>aiiNlGi while ihD« which ue iuppecled to be artr/n. PERSEUS, ET CAPUT MEDUSA. Pebseus is represented with a sword in his right hand, the head of Medusa in his left, and wings at hi» feet. It is situ- How la Baten KUtos situated? What i$ mOd of the various figurta thMdffftrtm omsteOatioiM esMMt 7 CHve an emmpU. Of what eoiuuUation does thatjlne ^uatmr 9rttanqftheMtle9quar»inauWhia*,eoiutUuUafart7 How l4 the constellaUon vspresantsd? 50 PICTURE OP THE HEAVENS. | OEC ated directly N. of the Pleiades and the Fly, between Andro- meda on the W. and Auriga on the E. Its mean declination is 49«>s lummous than the rest turned alternately in certain di zections either towards, or from us, will account for all the phenomena of periodical changes in the lustre of the stars, so satisfactorily, mat we certainly need not look out for any other cause." It 18 said, that the famous astronomer Lalande, who died at Paris in 1807, was wont to remain whole nights, in his old age, apon the Pont Neitfj to exhibit to the curious the variations in the brilliancy of the star AlgoL Nine degrees E. by N. from Algol, is the bright star Alge- nib, of the 2d magnitude, in the side of Perseus, which with Almaack, makes a perfect right angle at Algol, with the open part towards Cassiopeia. By means of this strikingly perfect figure, the three stars last mentioned may always be recoQ^- Qised without the possibility of mistaking them. Algenib may otherwise be readily distinguished by its being the brightest and middle one of a number of stars lying four and five degrees apart, in a large semicircular form, curving to wards Ursa Major. Algenib comes to the meridian on the 21st Decesiber, 15 minutes after Algol, at which time the latter is almost di* rectly over head. When these two stars are on the meridian, that beautiful cluster, the Pleiades, is about half an hour E. of it ; and in short, the most brilliant portion of the starry Heavens is then visible in the eastern hemisphere. The glories of the scene are uaspeakably magnificent; and the student who fixes his eye upon those lofty mansions of being, cannot fail to covet a loiowledge of their order and relations, and to "reverence Him who made the Seven Stars ana Orion." The Milky-Way around Perseus is very vivid, being un- doubtedly a rich stratum of fixed stars, presenting the most wonderful and sublime phenomenon "bf the Creator's power and greatness. Kohler, the astronomer, observed a beautiful nebula near the face of Perseus, besides eight other nebulous clusters in different parts of the constellation. The head and sword of Perseus are exhibited on the circumpolar map. That Tery 'bright star 23^ £. ol Algol, is CapeUa in the Charioteer. HiSTORT. — ^Perseus was the son of Jupiter and Danae. He was no sooner bom than lie was cast into the sea with his mother ; but being driven on the coasts of one of t!)e islands of the Cyclades, they were rescued by a fisherman, and carried to Polydcdtes, the king of the place, who treated tliem with great hu- tDanity, and intrusted them to the care of the priests of Minervd's Temple. His rising genius and manly courage soon made him a favourite of the gods. At a How may Algenib be distinguished? When is It on the meriJlanl How long alter AlgolY When these two stars are on the meridian, what bcautifUl cluster is ha]f an nour east of iti What Is the general appearance of the eastern hemlsphOTe at tn^"jnf' What is the appearance of the Milky Way anmnd Perseusi What nebula have ueea observed in t£i8 constellation! 1 1)2 PICTORE OF THE HEATEN9. £jASIu' great f«Mt of Polydectes, all the nobles were ejqMcted to present the kinff 'wUh e superb and beautiful lK>r8e ; but Perseus, who owed bis bene&ctor mncbi not wishing to be thought less munificent than the rest, engaged to bring taini the head of Medusa, the only one of the three Gorgons who was siibject to mor- tality. Thti names of the other two were Stheno and Eurig^e. They were r^ nreaented with serpents wreathing round their heads instead of hair, having yellow wings and brazen hands ; their bodies which grew indissolubly together, were covered with iii4)enetrable scales, and their very loolcs had the power of turning into btones all those on whom they fixed their eyes. To equip Perseus for this perilous enterprise, Pluto, the god of the infernal regions, lent him his helmet, wiiich had the power of rendering the wearer in> visible. Minerva the goddess of wisdom, fiimished him with her buckler, which was as resplendent as a polished mirrdir ; and he received finam Mercpry, wings for his feet, and a dagger made of- diamonds. Thus equipped, he mounted into the air, conducted by Minerva, and came xUpon the monsters who, with the watchful snakes about their heads, were all asleep. He approached them, and ^rith a courage which amazed and deUghted Minerva, cut off with one blow Me- dusa's head. The noise awoke the^wo immortal sisters, but Pluto's hehnet ren- dered Perseus invisible, and the vengeful pursuit of the Gorgoos proved firuitleas. "In the mirror of his polished shield Reflected, saw Medusa slumbers take, And not one serpent by good chance awake ; Then backward an unerring blow he sped, And from her body lopped at once her head." Perseus then made his wav through the air, with Medusa's head yet reeldns In his hand, snd from the blood which dropped from it as he flew, sprang aC those innumeral»le serpents that have ever smco infested the sandy deserta of Lybia. The victor Perseus, with the (Sorgon head. O'er Lybian sands his airy journey sped, The £ory drops distilled, as swift he flew, And from each drop envenomed serpents grew." The destruction of Medusa rendered the name of Perseus immortal, and ha was changed into a constellation at his death, and placed among the stars, with the head of Medusa by his side. CHAPTER III. DIRECTIONS FOR TRACING THE CONSTELLATIONS VTHICB ARE Olf THE MERIDIAN IN JANUARY. The constellations which pass our meridisn in the months of January, Febnv ary and March, present to us the most brliUant and interesting portion of the heavens ; embracing an annual number of stars of the highest order and bright* ness, all so conspicuously situated, that the most Inejperienced can easily trace them out. TAURUS. The Bull is represented in an attitude of rage, as if about to ]^lunge at Orion, who seems to invite the onset by pr(fro cations of assault and defiance. Only the head and snoulders of the animal are to be seen; but tiiese are so distinctly Wnat U the comparatHfeMUkm^ qfihe conaUOmtiona wMeh pom tHe meridian in Janutmf, February and Mtarchf Bow is Tmuus xepresentedl What parts of the animal are to be seem 3|JiP. ni.J TAVKU9. ^ marked that they cannot he mistaken. Taurus is now the second sign and third constellation of the Zodiac ; hut ante rior to the time of Abraham, or more than 4000 years a^o, the yemal equmox took place, and the year opened when the sun was in Taurus ; and the Bull, for the space of 2000 years, was the prince and leader of the celestial host. The Ram succeeded next, and now the Fishes lead the ye^r. The head< of Taurus sets with the sun about the last of May, when the opposite constellation, the Scorpion i»scenito rise in the S. E. It is situated between Perseus a«id Auriga on the north. Gemini on the east, Orion and fifidanus on the south, ana Aries on the west, having a mean declination of 16° N. It contains 141 yisible stars, including two remarkable clusters called the Pleiades and Hyades. The first is now on the shoulder, and the latter in the face of the Bull. - The Pleiades, according to fable, were the seven daughters of Atlas and the nymph Pleione,* who were -turned into stars, with their sisters the Hyade^j, on account of their amiable virtues and mutual affection. Thus we every where find that the ancients, with all their barbarism am! idolatry, entertained the belief that umblemished virtue and a meritorious life would meet their reward in the sky. Thus Virgil represent:! Magnus Apollo as bending from.the sky to address tlie youth lulus : — / *' Macte nova virtute puer ; sic ttur ad astra ; Diis genite, et geniture Deos." ** Go on, spotless boy, in the paths of virtue ; it is the way to the stars ; ofbprlnff of the gods thyself— so shalt thou become the father of gods." Our disgust at their superstitionj^nay be iu some measure mitigated, by seri* ously reflecting, that had some of these personages lived in our day, they had been ornaments in the Christian church, and models of social virtue. The names of the Pleiades are Alcione, Merone. Maia, Elecira, T ay eta, Sterope and Celeno. Merope was theVonly one who married a mortal, and on that account her star is dim amon^ her sisters. Although but six of these are visible to the naked eye, yet yDr. Hook informs us that, with a twelve feet telescope, he saw 78 stars ; and Rheita affirms that he counted 200 stars in this small cluster. The most ancient authors, such as ITomer^^Attalus, and Geminus, counted only tix Pleiades; but Simonides,yarro, Pliny, Aratus, Hipparchus, and Ptolemy« reckon them seven in number ; and it was asserted, that the seventh had been seen before tlie burning of Troy ; but this difference might arise from the dif- ference in distinguishing them with the naked eye. * Ik*. Button is of opinion that Atlas being the first astronomer who disco- vered these stars, called them by the names of the daughtera of his wife Pleione. What is the numerical order of Taurus among the signs and constellations of the Zodiac 1 What was iU position In the Zodiac before the time of Abraham? How lonn aw it continue to lead the celestial hosti What constellation succeeded next? where Is Taurus now ftituated? How many stars does it contain) Wliat «n»J*2S\'adas, gemlnosque Tnones, Armatumque auro circumspicit Oriona." " Observe the stars, and notes their sliding course. The Pleiads, Hyads, and their wat'ry force ; And both the Bears is caretxil to behold And bright Orion, aim'd witn oumish'd gold.' Indeed, this sagacious pilot was once sO intent in gazing upon the stais whfle at the helm, that he fell ovexfooard, and was lost to his companions. " Headlong he fell, and, straggling in the main, Cried out for heloing hands, but cried In vain.** From what circumstance do the Pleiades denve their name ? Vhat Is the brightest of the Pleiades calledl What is the siu of the rest? When are the Pleiades on the meridian? How much earlier do the etart rieci come to themerHiani cmd eet, tntrjg •ueeeedinff nifht J IC1.J TACRUt. M •even rtan culminate on the 6th Janoaryl MuAiply the 6 i the seas to that country, which derived fmm her its name. She was the aauffhter of Agenor, and princess of Phoenicia. She was so beautiful that . upitet oecame enamoured of her ; and assuming the shape of a snow- while bull, he mingled with the herds of Agenor, while Ruropa, with her female at- tendants, were gathering flowers in the meadows. Guropa caressed tlie bcaa tifnl animal, andat last had the courage to sit upon his back. The god now took advantage of her situation, and with precipitate steps retired towaras the shorCi and croiised the sea with Europa upon his hack, and arrived safe in Crete. Some supprse she lived about 1592 years before tlie Christian era. It is probaole- however, that this constellation had a place in the Zodiac before the G^'eeks be- Sn to cultivate a knowledge of tlie stars ; and that it vms rather an invention of e Egyptians or Chaldeans. Both the Egyptians and Persians worshipped a deity under this figure, by the name of Apis ; and Belzoni is said to have nund an embalmed bull m one of the notable sepulchres near Thebes. In the Hebrew 2Lodiac, Taurus is ascribed to Joseph. ORION Whoever looks up to this constellation and learns its name, will never forget it. It is too beautifully splendid to need a description. When it is on the meridian, there is then above the horizon the most magnificent view of the celestial bodies that the starry firmament aiSbrds; and it is visible to all the Habitable world, because the equinoctial passes throus^h the middle of the constellation. It is represented on celestial maps b^ the figure of a man in the attitude of assaultingthe Bull, with a sword in his belt, a huge club in his ris^ht hakd, and the skin of a lion in his left, to serve for a shield./ "~^ M^tmlius, a Latin poet, who composed five books ^on as<- tronomy a short time before the birth of our Saviour thuf descril)es its appearance : — ( " First next the Twins, see great Orio rise, His arms extended stretch o'er half the skies , His stride as large, and with a steady pace ' He marches ori, and measures a vast space ; On each broad shoulder a bright star dieplay'd, And three obliquely grace liis hanging blade. In his vast head, immers'd in boundless spheres, Three stars, less bright, but yet as great, he bears, But farther off removed, their splendour's lost ; Thus grac'd and arm'd he leads the starry host." The centre of the constellation is midway between tin poles of the heavens and directly over the equator. It is alsc about 8° W. of the solstitial colure, and comes to the me ridian about the 23d of January, The whole number of visible stars in this constellation is 78 ; of which, two are ol the first magnitude, four of the 2d, three of the 3d, and fif- teen of the 4th. Those four brilliant stars in the form of a long square oi What Is the ^ncral appearance of the constellation Orion? When this constellation Is on the meridian, wliat is the appearance of the starry firmament? To whom is it Wslble, and why? How is Orion represented on celestial maps? Describe its position. How is it situated with respect to the solstitial colure, and when is it on the meridian I What remarkable stars (brm the outline of the constellation I m.J ouoN. 9T pandielogram, intersected in the middle by th« " Thiee Stars," or " £11 and Yard^'labout 25<3 S. of the Bull's horns, form the outlines of^rion. T ixe twu up|n>| stars in the par allelogram are about 15^ N. of the two lower ones ; and. oeing placed on each shoulder, may be called the epaulets ot Orion. The brightest of the two lower 'ones is in the left foot, on the W., and the other, which is the least brilliant of the four, in the right knee. To be more particular : Bella- trix is a star of the 2d magnitude on the W. shoulder ; Be- telgnese is a star of the 1st magnitude, 7^^ E. of Bellatrix, on the E. shoulder. It is brighter than Bellatrix, and lies a Httle farther towards the north ; and comes to the meridian 30 minutes af^er it, on the 21st of January. These two form the upper end of the parallelo^m. Rig el is a splendid star of the 1st magnitude, in the lei) foot, on the W. and 15^ S. of Bellatrix. Saiph^ is a star of the 3d magnitude, in the rif ht knee, S\^ E. olRigel. These two form me lower end of tne parallelogram. " First in rank The martial star upon his shoulder flames*. A rival star illuminates his foot ; And on his ^rdle beams a luminary Which, in vicinity of other stars, Might claim the proudest honours." There is a little triangle of three small stars in the head ol Orion, which forms a larger triangle with the two in his shoulders. In the middle of the parallelogram are three stars of the 2d magnitude, in the belt of Orion, that form a straight line about 3° in length from N. W. to S. E. They are usu- ally distinguished by the name of the Three Stars, because there are no other stars in the heavens that exactly resemble them in position and brightness. They are sometimes de- nominated the Three IGnga^ because they point out the Hyades and Pleiades on one side, and Sirius, or the Dog-star on the other. In Job they are called the Bands of Orion ; while the ancient husbandmen called them Jacobus rod, and sometimes the Rake. The University of Leipsic, in 1807, gave them the name of Napoleon, But the more common appellation for them, including those in the sword, is the Ell and Yard. They derive the latter name from the circum stance that the line which unites the ^' three stars" in the belt measures just 3^ in length, and is divided by the central star Describe the two upper ones in the group. Describe the two lower ones. Give a more particular (leacripUon of the stars in the shoolder. How do jrou distinguish Be- telgnesefkom Bellatrix f When docs Betelgnese come to the meridian? Describe the stars which form the lower end of the paunillelogTam. What stars do you obserreln the head of Orion? Describe the siUiaUon and appearance of the " Three Starsi" Why •te Uiey called the three stars? What else are they denominated, and Tfoy,' ^w " ren to them by the ancients ? What by the University of Lcinslc » What were given , U tfao mote fionlliar term for them, and whence is tt derlvcdi 98 iMcruRC or the heavens. (jait. into two equal parts, like a yard -stick; thus serving as a graduated stand ird for measuring the distances of stars from each other. When therefore any star is described as bem^ so many degrees from another, in order to determine the dis- tance, it is recommended to apply this rule. It is necessary that the scholar should task h\i ingenuity only a few eveninn &i applying such a standard to the stars, before he will learn to ladge of their relative distances with an accuracy that will seldom vary a decree from the truth. The northernmost star in the belt, called Mintika, is less than ^o S. of the equinoctial, and when on the meridiai^ is almost exactly over the equator. It is on the meridian, the 24th of January.* The " three stars" are situated about 8° W. of the solstitial colure, and uniformly pass the meridian one hour and fifty minutes after the seven stars. There is a row of stars of the 4th and 5th magnitudes, S. oi the belt, running down obliquely towards Saiph, which forms the sword. This row is also called the Ell because it is once and a quarter the length of the Yard or belt. A very little way below T habit, in the sword, there is a ne- bulous appearance, the most remarkable one in the heayens. With a good telescope an apparent opening is discovered, through which, as through a window, we seem to get a glimpse of other heavens, and brighter regions beyond. As the telescope extends our knowledge of the stars and greatly fncrdases their visible number, we behold hundreos and thousands, which, but for thid aJmoiit divine improvement of our vision, had forever remained, unseen by us, in an unfathomable void. A star in Orion's sword, which appears single to the unassisted vision, is mttl> tiplied into six by the telescope ; and another, into twelve. Galileo found 80 io the belt, 21 in a nebulous star in the head, and about 500 in another part of Ovion. within the compass of one or two degrees. Dr. Hook saw 78 stars in the Pleiaaes, and Rheita with a better telescope, saw about 200 in the same cluster, and more than 2000 in Orion. About 9° W. of Bellatrix are eight stars, chiefly of the 4th magnitude, in a curved line running N. and S. With the con- cavity towards Orion ; these point out the skin of the Hon in his left hand. Of Orion, on the whole, we may remark with Eudosia : — " ne who admires not, to the stars is blind." History. — According to some authorities, Orion was the son of Neptune and queen Euryale, a famous Amazonian huntress, and possessing the disposition of * Tlioagh the position of this star, with respect to the equator, is the same at all times, whether it be on the meridian or in the horizon ; yet it appean to occupr this position, only when it is on the meridian. How may the distances of the stars from each other be measured by refisrence to the yanli How are the three stars situated with respect to the solstitial colure, and how with respect to the seven stars? Describe the stars which form the swonl of Oxion. What else is this row called i Describe the nebulous appeamnce which is visible te this cluster. WJuU other diacoveries hat the teJe$cope made in this contteUatiot^t What stars about 9^ W. of BellatrSr I MAP ni. I ORIOIL &M IklH motber, he became the greatest hunter in the world, and ev^n boasted tliat there was not an animal on earth which he could not conqaer. To punish thia \anity, it is said that a scorpion sprung up out of the earth and bit his foot, that he died ; and that at the request of Diana he was placed among the stars direcUx opposite to the Scorpion that caused his death. Others is&j that Orion had uo mother, but was the gift of the gods, Jupiter, Neptune, and Mercury, to a peasant of Boeotia, as a reward of piet]r> and that he was mvested with the power of walk- ing over the sea without wetting his feet In strength and stature he surpassea all other mortals. He was skilTed in the working of iron, from which he fitbri« cated a subterranean palace for Vulcan ; he also walled in the coasts of Sicily against the inundations of the sea, and built thereon a temple to its gods. Orion was betrothed to ,the daughter of CEnopion, but he, unwillinc to give up his daughter, contrived to' intoxicate the illustrious hero and put out iiis e^es on the seashore where he had laid himself down to sleep. Orion, finding himself blind when he awoke, was conducted by the sound to a neighbouring forge, where he placed one of the workmen on his back, and, by his directions, went to a place where the rising sun was seen with the greatest advantage. Here he turned his face towards tlie luminary, and, as it is reported, immediately recov- ered his sight, and hastened to punish the perfidious cruelty of (Enopion. The daughters of Orion distinguished tnemselvps as much as their father ; and, when the oracle had declared that Boeotia should not be delivered from a dreadful pestilence, before two of Jupiter's children were immolated on the altars, they joyfully accepted the offer, and voluntarily sacrificed themselves for the ^ood of their country. The deities of the infernal Vrgions were struck at the patriotism of the two females, and immediately two srars were seen to ascend ap from the earth, still smoking with their blood, and they were placed in the heavens in the form of a crown. Ovid says their bodies were burned by the Thebans, and that two persons arose from their ashes, whom the gods soon after changed into constellarions. As the constellation Orion, which rises at noon about the 9th day of March, and sets at noon about the 21st of June, is generally supposed to be accompani* ed, at its risuig, with great rains and storms, it became ejciremelv terrible to manners, in the early adventures of navigation. Virgil, Ovid, and Iforace. with some of the Greek poets, make mention of this. Thus Eneas accounts for the storm which cast him on the African coast on Uia way to Italy : — "To that blest shore we steer'd our destined way. When sudden, dire OrtoriTousVl the sea ; All charg'd with tempests rose the baleful star, And on our navy pour'd his wat'ry war." To induce him to delay his departure. Dido's sister advises her to "Tell him, that, charg'd with delucres of rain, Orion rages on the wintry main." The name of this constellation is mentioned in the books of Job and Amos, and iu Homer. The inspired prophet, penetrated like the psahnist of Hrael with the omniscience and power displayed in the celestial glories, utters this sublime injunction ; "Seek Him that maketh the seven stars and Orion, and turneth the shadow of death into mornin?." Job also, with profound veneration, adores ffls jwfiil majesty who "commandeth the sun and sealeth up the stars ; who alone spreadeth out the heavens, and maketh Arcturns, Orion, and Pleiades, and the chambers of the south :" And in another place, the Almisfhty demands of him- 'Knowest thou the ordinances of heaven 1 Canst thou bind the sweet influen- ces of the Pleiades, or loose the bands of Orion ; canst tliou bring fortti Mazza* roth in his season, or canst thou guide Arcturus with his sons 1" Calmet supposes that Mazzaroth is here put for the whole order of celestial baiiea in the Zodiac, which, by their appointed revolutions, produce the various seasons of the year, and the regular succession of day ancf night. Arcturua to he name of the principal star in Bootes, and is here put for the constellation *s«l£ The expression, hia aona, doubtless refers to Asterion and Chara. the two greyhounds, with whi^h he seems to be pursuing the great bear around the North pole. The following lines are copied from a work entitled " Astronomical Recrea- fons," by J. Green, of Pennsylvania, to whom dfie author is tadebted for inant aluable hints concerning the mythology of the ancient constellations. (K) PiCTURS or TBB REAVEir^ flAR ''When chininc winter spreads his azure *xieS) Behold Oriowt giant form arise ; ilis goiden girdle glitters on the sight, And the broad/alckion beams in splendour bright; A Uon'a brindled hide his bosom shields, And his right hand a ponderous weapon wieldsL The River's shining streams beneath him pour, And angr^ Taurus rages close before ; Behindliim Procyon barks, and ^rius growls^ While full in front, the monster Cetus howls. Bee bright Capella^ and Medusa there, With horrid serpents hissing through her hairi See Cancer too, and near the Hydra cUre, With roaring Leo, filled with furious fire. xfic timid Hare, the Dove with oHve green, And ArieSy fly in terrour from the scene ; The warrior Perseus gazes firom at>ove. And the Tvnn offspring of the thunderer Jofve, ho ! in the distance. Cassiope fair In state reposes on ner golden chair ; Her beauteous daughter^ bound, before ner stands, And vainly strives to free tier fettered hands j For aid she calli on royal Cepheus near. But shrieks from her reach not her/aMcr*« ear. See last of all, around the glowing pole, With shining scales, the spiry JOh-agon roll A grizzly Bear on eiHier side appears, Creeping with lazy motion 'mid the stars " These lines are easiW committed to memory, and would a&sfst the pupil in ve- tailin g the names of the constellations in this very interesting portion of (ha (lAtvena. ^ LEPUS. ■) The Hare. — This constellalion is situated directly sontli of Orion, and comes to the meridian at the same time; namely on the 24th of January. It has a mean declination 18^ S. and contams 19 small stars, of which, the four princi- pal ones are of the 3d magnitude. It may be readily distin- guished by means of four stars of the 3d magnitude, in the form of an irregular square, or trapezium. ZetcL of the 4th ma^itude, is the furst star, and is situa- ted in tne back, 5^ S. of Saiph, in Orion. About the same distance below Zeta are the four principal stars, in the legs and feet. These form the square. Jhey are marked Alpha. Beta, Gamma, Delta. Alpha and Beta otherwise caulea Arneb, form the N. W. end of the trapezium, and are about 3^ apart. Gamma and Delta form the S. E. end, and are about 2^^ apart. The upper ri^ht hand one, which is Ameb, is the brightest of the four, ana is near the centre of the con- Where is the constellation of tlie Hare situated? When does it come to the meri- dian? What is the whole number of Its stars? What is the magnitude of its princtasl ones ? How may it be distinguished? In what part of the animal are these stats nla- ced? Describe the principal star in Lepus. What are the distance and direction oftlM square tram Zeta? Describe the stars at each end of this square. Which is the ungbtest oftheiteir? MAP III.) COLCMBA — ERIDANU8. 01 £tellation. Four or fire decrees S. of Rigei are four very minute stars, in the ears of tne Hare. History.— This coostellatinn \a sdtnatcd about 18^ west of the Great Doci which, finom the motion of the earth, seems to be pursuing it, as the GreThoonds do the Bear, round tlie circuit of the sk^es. It was one of those animals which Orion Is said to have delighted in hunting, and which, for this reason, was mado into a constel^tion and placed near him among the stars. COLUMBA. Noah's Dove. — This constellation is situated about 16® S. of the Hare, and is nearly on the same meridian with the "Three Stars," in the belt of Orion. It contains only 10 stars ; one of the 2d, one of the 3d^ and two of the 4th mag- nitudes ; of these, Phaet and Beta are the brightest, and are about 2i° B,^ait, Phaet, the principal star, lies on the right and is the highest of the two ; Beta may be known by means of a smaller star just east of it, marked Gamma. , A line drawn from the easternmost star in the belt of Orion, 32^ di- rectly south, will point out Phaet ; it is also 11^° S. of the loAver left hand star in the square of the Hare, and makes with Sirius and Naos, in the ship, a large equilateral triangle. UiaroRY. — ^This constellation is so called in commemoration of the dove wliicU Noah ''sent forth to see if the waters were abated from olT the (ace of tlio Eound,*' after the ark had rested on mount Aiarat. "And the dovecame in to m in the evening, and lo, in her mouth was an olive leaf plucked off|' " The surer messenger, A dove i^ent forth once, and again to spy Green tree or ground, whereon his foot may light : The second time returning, in his bill An olive leaf he brings, pacific sign !" ERIDANUS. ^<. The Riyek Po.— This constellation meanders over a larg« and very irregular space in the hcaTtns. It is not easy, nor scarcely desirable, to trace out all its windings among the stars. Its entire length is not less than 130^ ; which, for the sake of a more easy reference, astronomers diyide into two sections^ the northern and the southern. That part of it which lies between Orion and the Whale, including the great bend about his paws, is distinguished by the name of the Northern stream ; the remainder of it is called the S&uUhem Btream, The Northern stream commences near Rigel, in the foot ▲ra these all the Stan that axe visible in this constellationf Describe the 8im«^?«wl^«» ErUnuls. What U Its entlTB length, and how is it dividedl By '«^at names are Uieaa se«Uonsdi*tingttish«df What are the course and dftrtamcs of the Northern sireemi 6 fi2 PICTURE OP THR HEAVENS f JAM of Orion, and flows out westeri)r, in a serpentine course nearly 40°^ to the Whale, where it suddenly makes a com- plete circuit and returns back nearly the same distance to- wards its source, but bending gradually down towards the south, when it again makes a similar circuit to the S. W. and nnally disappears below the horizon. West of Ri|(el there are five or six stars of the 3d and 4th magnitudes, archinf in a semicircular form, and marking the Jirtt bend of the northern stream. out 8° below these, or 19° W. of Rigel, is a bright star of the 2d magnitude, In the geeond bend of the northern stream, marked Oamma. This star cul- minates 13 minntes after the Pleiades, and one hour and a quarter before RigeL Passing Gamma, and a smaller star west of it, there are four stars neariy m a row, which bring us to the breast of Cetus. BP N. of Oamma, is a smaU star named Kiedy which te thought by some to be consiaerably nearer the earth than Birius TheeTniniy in the southern scream, is a star of the 3d magnitude, aooiit 17^ S. W. of the square in l^epus, and may be known by means of a smaller star, 1^ above it Ackemar is a brilliant star of the Ist magnitude, in the extremity of the southern stream ; but havif^ BOP of S. declination, can never be seen in this latitude. The whole number of stars in this constellation is 84 ; of which, one is of the 1st magnitude, one of the 2d, and eleven are of the 3d. Many of these cannot be pointed out by yer- h^ description ; they must be traced from the map. History. — ^Eridanus is the name of a celebrated river in Cisalpine Gkiul, also called Podus. Its modem name is Po. Virgil calls it the king of rivers. The Latin poets have rendered it memorable from its connexion with the fable of Phaeton, who, beicf a aon of Phcebus and Clymene, became a favourite of Venus, who intruste'J ui'n ivith the c^xe of one of her temples. Tliis favour of the goddett made hJm vain, and he soa^h'. of hia father a pul>lic and incontestable sign of his tend.^tretn, that should convince the world of his origin. Phoebus, after somo hei^f-Ation, made oath that he would grant him whatever he required, and no af*''LCT was the oath vltered, than — "The youth, transported, asks without delay. To guide the sun's brigbt chariot for a day. The god repented of the oath he took. For angiuish thrice his radiant head he shook ,*— My son, Pkys he, some other proof require, Rash was my promise, rash was thv desire — Not Jove himselC the; sky : But liow could you resist the orbs that roll In adverse whirls, and stem the rapid poll)" Phxbns represented the dangers to which he would be ezi>08ed in vain. Ho vidertook the aerial journey, and the explicit directions of his father were for- gotten. No sooner had Phaeton received the reins than he betrayed his igno- rance of the manner of guiding the chariot The flying coursers became sen- sible of the confusion of their driver, and immediately departed from the usual track. Pliaeton repented too late of his rashness, and already heaven and earth Describe its first bend? Describe the position of Gamma, and tell when It oomes tc 4^ Arehemar 7 What is the whole number of stars in this constellation? What Is tt^ ■oagnltode of ths principal ones ? n^^^mf MAP IIL] AURIGA. 63 were threatened with a aniversal conflagraUon as the consequence, when Jupi- ter, perceiving the disorder of the horses, struck the driver with a thunderboir, an:! nurled him headlong from heaven into the river Eridanns. His body, eon* snmed with fire, was found by the nymphs of the place, who honoured mm with a decent burial, and inscribed this epitaph upon his tomb : — ** Hie situa est Phaeton, currtu auriga patemi : Quene si non tenuit, tnagms tamen excidit autis." His sisters mourned his unhi^py end, and were changed bj Jupiter into poplars. **AI1 the long night their mourn fhl watch they keep, And all the day stand round the tomb and weep.'*— Ovid. It is ssJd the tears which they shed, turned to amber, with which the Pbeenl* ctaos and Carthaginians carried on in secrecy a most lucrative tnde. The great heat produced on the occasion of the sun's departing out of his usual course, is said to have dried up the blood of the Ethiopians, and turned their skins black s ind to have produced sterility and barrenness over the greater part of Lybia. ** At once from life and from the chariot driven, Th' ambitious boy fell thunderstruck from heaven." • •••••••• "The breathless Phaeton, with flaming hair, Shot from the chariot like a falling star, That in a summer's evening from the top Of heav'n drops down, or seems at least to drop, Till on the Po his blasted corpse was hurl'd, Far from his country, in the western world." The fiible of Phaeton evidently alludes to some extraordinary heats whick were experienced in a very remote period, and of which only this confused tra* dition has descended to later times. AURIGA. The Charioteer, called also the Wagoner, is represented on the celestial map by the tigure of a man in a declining posture, resting one foot upon the horn of Taurus, with a goat and her kids in his left hand, and a bridle in his right. It is situated N. of Taurus and Orion, between Perseus on the W. and the Lynx on the E. Its mean declination is 45^ N. ; so that when on the meridian, it is almost directly oxer head in New England. It is on the same meridian with Orion, and culminates at the same hour of the nis^ht. Both of these constellations are on the meridian at 9 o'clock on the 24th of January, and 1 hour and 40 minutes east of it on the 1st of January. The whole number of visible stars in Auriga, is 66, inclu- ding one of the 1st and one of the 2d magnitude, which mark the shoulders. Capella is the principal star in this constel- lation, and is one of the most brilliant in the heavens. It takes its name from Capella, the goat, which hangs upon the left shoulder. It is situated in the west shoulder of Auriga, Howls the constelatlon Auriga represented? Where is it situated? What Is Its mean decItnaUon, and what its posltfon on the meridian? How is It situated In reapwt to Oriont When are these constellations on the meridian? WJiat is the whole number of visible stars In Auriga? How many of the ist and M magnitude? What la the nams of the principal star, and whence derived i Wliere Is this situated l 64 PlCrnRE Of THE HEAVENS. | JAJf. 24» E. of AI50I, and 28^ N. E. of the Pleiades. It may be kno\vii by a little sharp-pointed triangle fonned by three stars. 30 or 40 this side of it, on the left. It is also IS© N. of E! Nath^ which is common to the northern horn of Taurus, and the right foot of Auriga. Capella comes to the meridian on the 19th of January, just 2^ minutes before Rio^el, in the foot of Orion, which it very much resembles in brightness. X MenkcUina, in the east shoulder, is a star of the 2(1 magnitude, 7|o E. of Capella, / had cuhninates the next minute after Betelguese, ^p S. of it. ThetOf in thb rcht arm. is a star of the 4th magnitude, S° directly soiith of Menkalina. It may oe remarked as a curious coincidence, tliat the two stars in the shoul- ders of Auriga are of the same magnitude, and just as far e^mrt as those in Orion, and opposite to them. Again, the two stars in the shoulders of Auriga, with the two in the shoulders of Orion, mark the extremities of a long, narrow parallelogr^in, lying N. and S., and whose leng h is just five times its hreadth. Also, the two stars in Auriga, and the two in Orion, make two slender and similar triangle^ both meeting in a common point, half way between tliem aa EL^alh, in the north- crn horn of Taurus. Delta, a star of the 4th magnitude in the head of Auriga, is about 9<^ N. of the two in the shoulders, with which it makes a triangle, about half the height of those just alluded to, witli the vertex at Delta. The two stars in the shoulders are therefore the base of two similar triangles, one extending about 9° N., to the head, the other 18^ 8., to the heel, on the top of the horn : both figures together resembling an elongated diamond. Delta in the head, Menkalina in the right shoulder, and Theta in the arm of Auriga, make a straight line with Betelguese in Orion, Delta in the square erf the Hare, and Beta in Noah's Dove ; all being very nearly on the same meridian, i^ w. of the solstitial colure. "See next the Goatherd with his kids ; he shines With seventy stars, deducting only four. Of which Capella never sets to us,* And scarce a star with equal radiance neams Upon the earth : two other stars are seen Due to the second order." — Eudosia. HuTO&r.-^he Greeks give various accounts of this constellation ; some snp pose it to be Erichchonius, the fourth king of Athens, and son of Vulcan ancFfln. nerva, who awarded him a place among the constellations on account of his many osefkii inventions. He vras of a monstrous shape. He is said to have invented chariots, and to have excelled all others in the management of horses. In al^u- ^ion to this, Virgil has the following lines :-~ ** Primus Erichthonius currus et qui^uor ausus Jungere equos, rapidisque rotis insistere victor." Georgic. Lib. iii. p. 113 "Bold Erichthonius was the first who join'd Four horses for the rapid race design d. And o'er the dusty wheels presiding sate " — Dryden. Otiier writers sav that Bootes invented the chariot, and that Auriga was the ■on of Mercury, and charioteer to CBnomaua king of Pisa, and so experienced, Jiat he rendered his horses the swiftest in all Greece. But as neither of these fables seems to account for the goat and her kids, it has been supposed that they refer to Ahuathasa and her sister Melissa, who fed Jupiter, during his infancy, * In the latitude of London ; but In the latitude of New t^figlanil, Capella disappears kelow the horizon, in the N. N. V., for a few hours, and then reappears In the N. N. R How may it be known? "What are its distance and dirortion flrom El Nath, in th« bom of Taurasi- When does Capella come to the meridian ? Deaerlbe the star in th^ east ahoitlder i}f Auriga. Describe Theta. What euritms eoinefdencc exists between the stars in the shoulders qf Auriga and those in the shoulders fif Orion ? Describe tha situation cf Delta. The hco stars in the shoulders (if Auriga Jbrm the base qfttpo trt' angles: please describe them. liTua stars inAurisfo, Orion, the Hare, and the E>one. are on the same met idian ? Umo fiir is this line qf stars wctt of the solstitial coku e 7 MAP til. I CAMELOPARDALUS. — THE LYNX. 65 iritii goat's milk, and that, as a reward for their kindness, they wem |tlaced fa the heavens. But there is no reason assigned for their being placed in the aroM of Auriga, and the inference is unavoidUiblei that mjrthology is in fault oc Jiia poinu Jtcmieson is of opinion that Auriga is a mere type or scientific symbol of tb« beaotiiul fable of Pliaeton, because he was the attendant of Fhcebos at that r»> mote period when Taurus opened the year. CAMELOPARDALUS. Tb£ Gamelopard. — This constellation was made b/ He- velius out of the unformed stars which lay scattered lietween' Perseus, Auriga, the head of Ursa Major, and the Pole Star. - It is situated mrectly N. of AUriga and the head of the Lynx, and occupies nearly all the space between these and the pole. It contains 58 small star^; the five largest of which are only of the 4th magnitude. The principal star lies in the thigh, and is about 20° from Capella, in a northerly direction. It marks the northern boundary of the temperate zone; being less than one degree S. of the Arctic circle. There are two other stars of the 4th magnitude near the right knee^ 12° N. E» of the first mentioned. They may be known by their standing 1° apart and alone. The other stars in this constellation are too small, and too much scattered to invite observation. HiSTORT.— The Camelopard is so called from an animal of that name, peculiar U> Ethiopia. This animal resembles both the camel snd the leopanL Its body is spotted like that of the leopard. Its neck is about seven feet long, its fore and hind legs, from the hoof to the second joint, are nearly of the same length; but from the second joint of the legs to the body, the fore legs are so long in com- parison with the hind ones, that no person conld sit upon its back, without in* stantly sliding off as from a horse that stood up on his hind feet CHAPTER IV. DIRECTIONS FOR TRACING THE CONSTELLATIONS WHICH ASE Oil THE MERIDIAN IN FEBRUARY. THE LYNX. The constellation of the Lynx, like that of the Camelopard, exhibits no very interesting features by which it can be dis- unguished. It contains only a moderate number of inferior stars, scattered over a large space^. of Gremini, and between Auriga and Ursa Major. The whole number is 44, including Of what was the Camelopard madei Where Is it situated 1 What is the whole num- ber of stars? WhatlB the magnitude of the largest? What are the na«»?„^'^^»\\!°; of the principal one? Where are the other principal stars situated? Ho?;™*yJ2®3r be tao^l ^hewe does it derive U9 name J What is Ihe situation of the i-ynxl What are tho number and magnitude of Its -^tars 1 . 6 66-. ricTURE or tbe beaveN9> [feb. onW three that are so large as the 3d magnitude. The larapesi of these^ near the mouth, is in the solstitial colure, 14^^ N. uf Menkalma, in the E. shoulder of Auriga. The other two prin- cipal stars are in the brush of ^e tau, 3^^ S. W. of another star of the same brightness in the mouth of the Lesser Lion, with which it indikes a small triangle. Its centre is on the meridian at 9 o'clock on the 23d, or at half past 7 on the 1st, of February. HisTOBT —This constellation takes its name from a wild beast which is said to- be of the genus of the wol£ \ GEMINI. ^ The Twins. — This constellation represents, in a sitting posture, the twin brothers. Castor and Pollux. Gemmi is the third sign, but fourth constellation in the order of the Zodiac, and is situated south of the Lynx, be- tween Cancer on the east, and Taurus on the west. The orbit of the earth passes through the centre of the constella- tion. As the earth moves round in her orbit from the first point of Aries to the same point again, the sun, in the mean- time, will appear to move through the opposite signs, or those which are situated right over against tne earth, on the othei side of her orbit. Accordingly, if we could see the stars as the sun appeared to move by them, we should see it passing over the constel- lation Gremini between the 21st of June and the 23d of July -, but we seldom see more than a small part of any constellation through which the sun is then passing, because the feeble lustre of the stars is obscured by tne superior effulgence of the sun. When the son is just entering the outlines of a constellation on the east, its western limit may be seen in the mominx twilight, just above the rising sun. So when the sun has arrived at the western limit of a constellation, the eastern part of it may be seen lingering in the evening twilight, just behind the setting sun. Under other circumstances, when the sun is said to he in, or to enter, a particu- lar constellation, it is to be understood that that constellation is not then visible, but that those opposite to it, are. For example : whatever constellation sets with the sun on any aay, it is plain that the one opposite to it must be then rising, and continue visible through the night. Also, whatever constellation rises and sets with the sun to-day. will, six months hence, rise at sun-setting, and set at sun-rising. For example : the sun is in the centre of Gemini al)out the 6th of Describe the position of the largest Describe the position of the other two prindpal stars. Whs^ are their distance and direction f^om tbe one in the head? When is it* centre on the meridian? Describe the position and appearance of the Twins. What Is the relative position of Gemini among the signs and constellations of the 2Soditic> How is the oxblt of the earth situated, with respect to these constellations? How do the sun and earth appear to move through these signs? When does the sun appear to pass through the constellation Gemini 1 Do we usually see the constellations wbOe the sun isnisslDg through them? Under what drcunutancea can v>e we eame part qf them? Whm the nm U in or entering any canttOlationj are the oppoeite amtteOa tUmevifMeolrnM? If a eon^eUation rite wWt the tun to-day, how wUlUrUe wig .wumthe henceJ Give an example. MAP I11.J OEMOII, 07 Jnljr, and must rise and set wkh it on that day ; conaeqaeBrly, aijc monUw tnm tbat time, or abontthe 4th of January, it will rise in the east Juat when the nm ia setting in the west, and will come to the meridian at midnij|ht ; being then ez* acUy opposite to the sun. Now as the stars gain upon the sim at the rate of two honra etery moolhi ft follows that the centre of this consteliation will, on the 17th of February. eooM to the meridian three lioors eartier, or at 9 o'dock in die eT«Bliig» It would be a pleasant exercise for students to propose questioiia to each odier^ cnmewhat like the followinf :->What sodiacal constellation will rise and set with the son To-day 1 What (me will rise at sun-setting 1 What consteOatfott is three Buura high at sun-set, and where will it be at 9 o'ck>ck 1 What eonalel> iation rises two hours before the soni How many days or months henee, uid iLwhat hour of the evening or morning, and hi what piurt of the sky shall we tee the constellation whose centre is now where the sun ia Y *c., Ac ^ In solving these and similar questions, it may be remembered that the aan is ^f in the vernal equinox about the 2l6t of March, from whence it advances throi^ r one si^ or constellation every succeMing month thereafter ; and that eaeh cm^ tteOaftoH is one mouth in advance of the sign of that name : wherefore, reckon Pisces in March, Aries in April, Taurus in May. and Gemini in June, *c ; be> finning with each constellation at the 21at, or 22d of the month. Gremini contains 85 stars, including one of the 1st, one of the 2d, four of the 3d, and seven of the 4th ma^tudes. It ia readily recognised bv means of the two princi}>al stars, CoB' tor and Potliur, of tne 1st and 2d magnitudes, in the head of the Twins, about 4^° apart. There being only 11 minutes' difference in the transit of these two stars over the meridian, they may both be consid- ered as culminating at 9 o'clock aoout the 24th of February. CastoTy in the head of Castor, is a star of the 1st magnitude, 4Jo N. W. of Pollux, and is the northernmost and the bright- est of the two. Pollux, is a star of the 2d magnitude, in the head of Pollux, and is 4J<> S. E. of Castor. This is one of the stars from which the moon's distance is calculated in the Nautical Almanac. "Of the famed Ledean pair, One most illustrious star adorns their sign. And of the second order shine twin lights/' The relative magnitude or brightness of these stars his undergone considerable changes at different periods ; whence I it has been conjectured by various astronomers that Pollux I must vary from the 1st to the 3d magnitude. But Herschel, who observed these stars for a period of 25 years, ascribes the variation to Castor, which he found to consist of two stars, very close together, the less revolving about the larger once in 342 years and two months. Bradiy and Maskelvne found that the line joining the two stars which form CiHIor was, at all times of the year, paraUel to the Une joining Castor and FODox ; and that b wer« about to be married, and resolved to supplant their rivals : a battle ensued, fai which Castor killed Lynceus, and was himself killed by Idas. PoUoz revenged the death of his brother by killing Mas ; but, being himself immMrtaly snd moat traderly attached to his deceased brother, he was unwilling to survive him ; ha therefore entreated Jupiter to restore him to life, or to be deprived himself of imioortality : wherefore, Jupiter permitted Castor, who had been slain, to diar« the immortality of Pollux-; and consequently, as long as the one was upon earth, ao loi^ was the other detained in the mfemal re^pons, and they altemataly liv«a and died every day. Jupiter also further rewarded their fratenml attaeiim«iit by changing them both into a constellation under the name of GemiM^ TVAm^ which, it is strangely pretended) never appear together, but when one rises the other sets, and so on alternately. " By turns they visit this ethereal sky, And live alternate, and alternate die."— £fiMiMr. ** Pollux, offering his alternate life, Could free his brother, and could daily go By turns aloft, by turns descend below."— l^rgiL Castor and Pollux were worshipped both by the Greeks and Romans, who sacrifice. * It Is not difficult to deduce the moral of this fkble. The selfishness and caprice of '<^ human friendship furnish daily illustrations of IL While the good man, the philau- throptst, or the public benefoctor, la in affluent circumstances, and, with a heart to devise, has the power to minister blessings to his numerous beneficiaries, bis virtues are the general theme : but when adverse storms have changed the ability, though they could not shake the will of their beneflustor, he is straightway pursued, like Ac- tseon. by his own hounds ; and, like Actaeon, be is " torn to tlie ground" by the fimn that fed upon his bounty.— L. Q. C L. ^ ^ ^ yhat luinie is usually given to the Little Dogi When does Procyon rise and eulml* ££^tTi% "ifl*«* *** ^^ Dog star? What name, fbr this reason, was given to this eonstellationi >ur HI. I MONOCEBos — cakis uajob. *1 MONOCEROS. The Unccohn. — This is a modem constellation, which was made out of [he unformed stars of the ancients that laj scat- tered over a large space of the heavens between the two D(^. It extends a considemble distance on each aide of ihe equinoctial, and its centre is on the same meridian with It contains 31 small stars, of which the seren principal ones are of only the 4th magnitude. Three of these an Bimated in the head, 3° or 4° apart, farming a straight liike N. E. and 3. W. about 9° E. of Betel^ese in Orion's shoul- der, and about the same distance STof Alhena in the foot ot the Twins. The remaining stars in this constellation are scattered am a large space, and being very small, are unworthy of putieo- lai notice. HisTOR IE Dnlcora or KhJntKsnw. H li Iboui the ETowiDg ODt of Iba niMir* * *~ lbr«head L<>piii Bud to be rtrj Ion Nuura mien, it prH^pitUn iuelf t . theiopsc lahoirvvhichHBMuttwwhato force of i herebT. Spunuioii Infomu ik thai Ih« e coribi innmU, bubeen Cnmd Ttae rt I in Bengal, Rum, Cochin Chln^ CANIS MAJOE. The Great Dog.— This inlereBtiiig constellation is r hemisphere with a lustre which is unequalled by any other star in the firmament. Its distance from the earth, though computed at 20 millions of millions of miles, is supposed to be less than that of any other Starr a distance, howeyer, so great that a cannon bal^ which Sies at the rate of 19 miles a minute, would be two millions of years in passing over the mighty interval; while sound, moTHig at the rale of 13 miles a mmute, would teach Sirius in little less than three millions of years. UT&lMgni'wlBofH.prlniMBilone.l rtt^^rtbo IhOM Uilhe b™L^t)BJ«». ttj^ tlaw vouldeo 72 PICTURE OF THE HEAVEN^. i FSB. It OUT be shown In the same imuincr, that a ray of Ii|;ht, which ocrupirs oniy 6 minutes and 13 seconds in coming to us from the sun, which is at the rate of neailT two hundred thousand miles a second, would be 3 years and 82 days in n$atiam through the vast space that lies between Sirius and the eanh. Conse- quentlyf were it blotted from the heavens, its light would continue visible to ub 8>r a period of 3 years and 88 days after it had ceased to be. If tne nearest stars give such astonishins results, what shall we say of those which are.sitttated a thousand times as tu beyond these, as tlieseare from usi In the remote aees of the world, when every man was his own astronomer, the rising and setting of Sirius, or the Dog^ star, as it is called^ was watched with deep and various so- licitude. The ancient Thebans, v/ho first cultivated astro- nomy in Kgypt, determined the length of the year by the numoer of its risings. The Egyptians watched its rising with mingled apprehensions 'of hope and fear; as it was ominous to them of agricultural prosperity or bligh|ing drought. It foretold to them the rising of tne Nile, which they called Siris, and admonished them when to sow. The Romans were accustomed yearly, to sacrifice a dog to Sirius to render him propitious in nis influence upon their herds and fields. The eastern nations generally believed the rising of Sirius would be productive of great heal on the earth. Thus Virgil :— " Tuni steriles ezurero Sirius agros : Ardebant herbss, et yictum seges eegra negaliat." "Parched was the gr&ssj and blighted was tlie com : Nor 'scape the beasts ; for Sinus, from on higli, With pestilential heat infects the sky." Accordingly, to that season of the year when Sirius rose with the sun and seemed to blend its own influence with the heat of that luminary, the ancients gave the name of Dog-- days, {Dies Caniculares). At that remote period the Dog- days commenced on the 4th of August, or four days after the summer solstice, and lasted forty days or until the 14th of September. At present the Dog-days begin on the 3d of July, and continue to the 11th of August, being one day less than the ancients reckoned. Hence, it is plain that the Dog-days of the moderns have no reference whatever to the rising of Sirius, or any other star, because the^me of their rising is perpetually accelerated by the precession of the e(]^uinoxed: they have reference then only to the summer solstice which never "changes its position in respect to the seasons. » ^^*'5*f <•%***• earning from Siriua to the earth 7 Suppone thie star were now to he f'w'fa Jrom the heavens, how long btifbre Us (winkling would expire 7 How was the nsing or BlrluB regnded in the remote a^s of tbo world ? What use was made of II aL^^iS*^^* J??**^' -9Sy ^^ theEgypUans re»irtl It, and for what reason? ▼tatdUltfbietel to them? What did the Romans offerln sacrifice to Sirius annually? lOSSlt^^S^ ^^ It regaxded by the eastern nations generally? What season of the jyar did the ancients t^lDogdaysl When did thewj begin, and how long did tS gj^^w«ent,whwi do they begin and end' Have our Dc^uajs any reltoSmcJ^ MAP 111."] CAMS MAJOR. 73 The |ime of Sinus' rising varies with the latitude of tlte pkce, and in the mmm latitude, is sensibly changed ailer a course of years, on account of the prece«> sion at the equinoxes. This enables us, to determine with approximate accu- r»cy, tlie dates of many events of antiquity, which cannot be well determined by other records. We do not iusow. for instance, in wliat precise period of the world Hesiod iflourished. Yet he tells us, in liis Opera et Diea^ lib. li. v. 18& tliat Arcturus in his time rose heliacall^, 60 davs alter the winter solstice, which, then was in the 9th degree of Aquarius, or 39<^ beyond its present position. Now 39^ ; 50^" »2794 years since the time of Hesiod, which corresponds very nea^jr with history. When a star rose at sun-setting, or set at son-rising, it was called the Achronu cai rising or setting. When a planet or star appeared above the horizon just before the sun, in the morning, it was called the Heliacal rising of die star; and when it sunk below the horizon immediately afler the sun, in the evening, it was called the Heliacal setting. According to Ptolemy, stars of the first magnitude are seen rising and setting when the sun is 12^ below the horizon ; stars of the 2d magnitude reuuire theisun's depression to be i3<=> ; stais of the 3d magnitude, liP^ and so on, allowing one degree for each magnitude. The rising and setting of the stars described in this way, since this mode of description oden occurs in Hesiod, Virgil, Columella, Ovid, Pliny, &c. are called poetical rising and set- ting. They served to mark the times of religious ceremonies, the seasons al> lotted to the several departments of husbandry, and the overflowing ^rl^Kile The student may be perplexed to understand how the Dog-star, which he seldom sees till mid-winter, should be associated with the most fervid heat of summer. This is explained by considering that this star, in summer, is over our heads in the daytime^ and in the lower hemisphere at night. As " thick the floor of heayen is inlaid with patines of bright gold," by day, as by night ; but on accoxmt of the* superior splendour of the sun, we cannot see them. Sirius is situated nearly S. of Alhena, in the feet of the Twins, and about as far S. of the equinoctial as Alhena is N. of it. It is about 10° E. of the Hare, and 26° S. of Be- iqjguese in Orion, with which it forms a large equilateral triangle. It also fonns a similar triangle with Phaet in the Dove, and Naos in the Ship. These two triangles being joined at their vertex in Sirius, present the figure of an enormous X, called by some, the Egyptian X. Sirius is also pointed out by the direction of the Three Stars in the belt of Orion. Its distance from them is about 23°. It comes to the meri* dian at 9 o'clock on the 11th of February. Mirzam, in the foot of the Dog, is a star of the 2d magni- tude, o^o W. of Sirius. A little above, and 4° or 5^ to the left, there are three stars of the 3d and 4th magnitudes, form- ing a triangular figure somewhat resembling a dog's head. ■ II I ■ , , I III » What i» meant by the Achronieal riaing^ and setting qf the stars 7 What, by thew Haiaeal rising and setting J By whom were the terms thus applied, and what wa^ these risings and settings catted J What did they serve 1 Explain how It is, that the Doe-star, wlUcb is seldom seen till mid-winter, should be associated wltli the mott fervid heat of summer. Are theie as many stars over our head In the daytime as m the night? Describe the situation of Sirius. What is its position with regaiU to B^ telfluese and Procyon, and In conuexlon with them what figure does « fonjil-J^S what other stars does it fonn a similar triangle) What is ih© appearan^ ^rtSS^SS triangles taken together? How else is Sirius pointed outi Descxibd the poMiioa ana magnitude of Mirzam. What stars mark the head of the Dogi 7 74 PICTUR9 or THE tir-VVEiVS. JMAL. The brightest of them, on the left, is called Muliphen. If entirely disappeared in 1670, and was not seen again for more than 20 years. Since that time it has maintained a steady lustre, Wesen is a star of between the 2d and 3d magnitudes, in the back, 11® S. S. E. of Sirius, with which, and Mirzaun in the paw, it makes an elongated triangle. The two hinder feet are marked by Naos and Lambda, stars of the 3d and 4ih magnitudes, situated about 3° apart, and 12® directly S. of the fore foot. This constellation contains 31 visible stars, including one of the 1st magnitude, four of the 2d, and two of the 3d ; all of which are easily traced out by the aid of the map. HinoBT.-^^ManiUas, a Latin poet who flonriahed in the Aufoatan age, wrote an admirable poem, in five books, upon the fixed stars in which he tlios speaks of tills constellation :— "All others he excels; no fairer lleht Ascends the skies, none sets so clear and bright." But EuBOSU best describes it : — " Next shines the Do^ with sixty-four distinct ; * Fam'd for pre-eminence in envied song, Tlieme ofllomerie and Virgilian lavs : His fierce mouth flames with dreaded Siriu» ; Throe of his stars retire with feeble beams." According to some mythologists, this constellation represents one of Orion't hounds, which was placed in the sky, near this celebrated huntsman. Others say it received its name in honour of the doc given by Aurora to Ccphatus^ which surpassed in speed all the animals of his'species. Cephalnii, it is said at- tempted to prove this by running him against a fox, wliicn, at that time, was thought to be the fleetest of all animals. After they had run tosrether a long time without eithsr of them obtaining the victory, it is said that Jupiter was «o much gratified at the fleetness of the dc^ that he assigned hiin a place in the heavens. But the name and form of this constelktiun are, no doudt, d<>rived fn>m the Egyptians, who^ carefullv watched its rising, and by it judged of the swelling ot the Kile, which they called Siris, and, in their hieroglyphical manner of writing, ^ce it was as It were the sentinel and watch of the rear, represented it under the figure of a dog. They observed that when Sirius became visible In the east, just before the morpinf dawn, the overflowing of the Nile immediately followed. Thus it warned them, uke a faithful dog, to escane from the region of the inon dttkm. CHAPTER V. DIBECTIONS FOR TRACING THE CONSTELLATIONS WHICH ARE O^ THE MERIDIAN IN MARCH. ARGO NAVIS. The ship Argo. — This constellation occupies a large space In the southern hemisphere, though but a small part of it can S Which is the brightest of these, and what xemarkable circumstance in Its htsttXTf owh^ it APPMied since Its return iDescrlbe the situation and magnitude of Wesen j .. %P.f*^ 'Sf'^^il^ !^^^ *^," ^^=* *■ tl>« number of vUlble stars In tUsoan. ■teOauccY DescrflM the conitellation Argo Navis? » .m«. m uub con* 1 Kk9 III.^ AHGO NAVI^ 75 be seen in the United States. It is situated S. £. of Canin Major, and may be known by the stars in the prcw and deck of the ship. If a straight line joining Betelguese and Sirius, be pro diUon was finished, and Jason had returned in triumph, he ordered her to be drawn ashore at the isthmus of Corinth, and consecrated to Neptune, the god of the sea. Bir Issac Newton endeavours to settle the period of this expedition at about 30 Years before the destruction of Troy ; and 43 years afler the death of Solomon. ur. Bryant, however, rejects the history of the Argonautic expedition as a mere fiction of the Greeks, and supposes that this group of stars, which the poets de- nominate Argo Navis, refers to Noah's arlc and the deluge, and that the &ble of the Argonauuc expedition, is founded on certain Eeyptian traditions that related to the preservation of Noah and his family during the flood. CANCER. The Crab, is now the fifth constellation and fourth sign of the Zodiac. It is situated in the ecliptic, between Leo on the E. and Gemini on the W. It contains 83 stars, of which, one is of the 3d, and seven of the 4th magnitude. Some place the first-mentioned star in the same class with the other seven, and consider none larger than the 4th magnitude. Beta, is a star of the 3d or 4th magnitude, in the south- western claWj IQo N. E. of Procyon, and may be known from the fact that it stands alone, or at least has no star of the «ame magnitude near it. It is midway between Procyon and Acubens. AcubenSy is a star of similar brightness, in the southeastern claw, 10° N. E. of Beta, and nearly in a straight line with it and rrocyon. An imaginary line drawn from Capella through Pollux, will point out Acubens, at the distance of 24° from Pollux. It may be otherwise distinguished by its standing between two very small stars close by it in the same claw. Tegmine, the last in the back, appears to be a small star, of between the 5th and 6th magnitudes, 8Jo in a northerly direction from Beta. It is a treble star, and to be distinctly seen, requires very favourable circumstances. Two of them are so near together that it requires a telescopic power of 300 tQ separate them. About 7° northeasterly from Tegmine, is a nebulous cluster of very minute stars, in the crest of Cancer, sufli ciently luminous to be seen by the naked eye. It is situated in a triaimilar position with regard to the head of the Twins and the Littl« Dog. It is about 20^ W. of each. It may otherwise be discovered by means of two conspicuous stars What to the relative position of Cancer among the signs and constellations of the Zodiac? How Is It siniated? What ate the number and mafrnltnde of Its stanij Where IB Beta situated, and how may it be kno^vIll Which way from Procyon and Acubens t Describe Acubens. What are Its distance and direcUon from Pollux? How may it ba otherwise knowni Describe Tegmine. There Is a remarkable cluster in this con. stellatlon-describe its position. How may It otherwise be discoveiw^*'' M^r UK 1 CAXCFB. < i ol tue -ith magnitude lying one on either side of it, a( the i1i6- tauce of about 2<^, called the northern and southern AscUk By some of the Orientalists, this cluster was denominated Pr firom the solstitial colure. There are several other double and nebulous stars in thia constellation, most of which are too small to be seen ; and. in- deed, the whole constellation is less remarkable for the bril- liancy of its stars than any other in the Zodiac. The sun arrives at the sign Cancer about the 21st of June, but does not reach the constellation until the 23d of July. The mean right ascension of Cancer is 128^. It is conse- quently on the meridian the 3d of March. A few degrees 8. of Cancer, and about 17^ E. of ProcYon, are four stars of tt.e 4th ma^itude, 3^ or 4^ apart, X{uch mark tlie head nr Hydra. This conateUar lion will be described on Map Ilk The beginning of the sign Caneer (nut the constellation) is called the Troptc tf Cancer^ and when the son arrives at this point, it has reached its atmost limit of north declination, where it seems to remain stationary a few days, before it begins to decline again to the\ south. This stationary attitude of the sun ts called the summer aolstice ; from two Lidn words sicnifyin^ the mn's standing' atilL The distance from the first point of Cancer to me equmoctial, which at present, i? 23° 27!', is called the obliquity of the etliptie. It is a remarluble and well as- certained fact, that this is conunually (prowing less and less. The tropics are ■lowly and steadily approacliinc the equmoctial, at the rate of about half a second every year ; so that the sun (foes not now come so iar north of the equator fai summer, nor decline so Iar south in winter, as it must have done at the creation, by nearly a degree. lIisTOBY.— In the Zodiacs of Esne, and Oenden, and in most of the astrologlcai remains of Egypt) a Scarabnus, or Beetle, is used as the symbol of this sign ; but in Sir WiUiam Jones's Oriental Zodiac, and in some others found in India, we meet with the figure of a crab. As the Hindoos, in all probability, derived their Icnowledge of the stars from the Chaldeans, it is supposed that the figure of the crab, in mis place, is more ancient than the Beetle. In some eastern representations of tiiia sign, two animals, like asses, are found in this division of the Zodiac; and as the ChaJddc name for the ass raav be translated fimddt'new, it is supposed to allude to the discolouring of the Nile, which liver was rising when the sun entered Cancer. The Greelu, in cojiving this sign, have placed two asses as the appropriate symbol of it, which BtUl re- What Is the name of this cluston What is its suDpearance to the naked eye, and for what has It been mistakml How is the star called the southern Asellus, situatedi with respect to the ecilpttcT What other stars in this ewMOkuion? At what time ioes the sun enter the tign Cancer? At what time the cmuteBmUmJ WhtreU As tropic qr Cancer eUuaUd? When the sun reachea thia pofn/ tohat i« •«« SCiSlit. tl^iSnl What UthUetatitmaru attitude qfOteetmeaUeiJ^^^^ ^the ecliptic J What remarkable Jket in respect to thU iUtance ? Doet 'He «W» •« U^Mity qfthe tropioi, ^ . 7* 78 PICTURE Of tHE HEAVENS* [APRIL. nu^n. Th«y Axplafn their reason, howcrer. for adopting thla figure, hj wajfng thai these ar« the animals that aaatsted Jupiter in his victory over the giants. Dopuis acronncs for tlie oricin of the asaea in the following words :— Le Can- cer. 4(1 soiit tea itnilea appellees )es tenea, forme Timpreinte du paviUon d* Is* ■achar que Jacob assimile k V ane. Mvrhologista give fiiffereut accounta of the origin of this constellation. The prevailing opinion ia, that while Hercules waa engaged in hia Taroous contest with the dreadful Lerncan monster, Juno, envious of the fame of hia achieve- uentSi sent a ses'crab to bite and annoy the hero's feet, but the crab being soon deqnttehed, the goddess to reward its services, placed it among the constella- tions. -**The flcorpkm's claws here clasp a wide extent. And here the Crab's in lesser clasps are bent" CHAPTER VI. DIBECTIONS FOR TRACING THE COlfSTELLATfOlTS WHICH AI» 09 THE MERIDIAN IN APRIL. LEO. 'The Lion. — This is one of the most brilliant constollaiions in the winter hemisphere, and contains an unusual number of very bright stars* It is situated next E. of Cancer, and directly S. of Leo Minor and the Great Bear. The Hindoo Astronomer. Varaha, says, " Certainly the southern solstice waa once in the middle of Asleha iLeo) \ the northern in the first degree of Dhatt- iahta" (.Aquaritut). Since that time, the solstitial, as well as the equinoctial pointy have gone backw^ds on the ecliptic 75°- This divided by SOJ^", gives £373 years ; which carry us back to the year of the world 464. Sir'w. Jones^ says, that Varaha lived when the solstices were in the first degrees of Cancer and Capricorn ; or about 400 years before the Christian era. Leo is the Jifth sign^ and the siccth constellation of the Zo diac. The mean right ascension of this extensive group is 150<5, or 10 hours. Its centre is therefore on the meridian the 6th of April. Its western outline, however, comes to the meridian on the 18th of March, while its eastern limit does not reach it before the 3d of May. This constellation contains 95 visible stars, of which two are of the 1st magnitude, two of the 2d, six of the 3d, and fifteen of the 4th. «Two sprendid stars of highest dignity, Two. of the second class the Lion boasts, And justly figures the fierce sunuuer's rage.' The principal star in this constellation is of the 1st ma;^ nitude, situated in the breasrt of the animal, and named He- gulus, from the illustrious Roman consul of that name. What is the general appearance of the constellation Leo? Where is it situatedl What is the relative order among the signs and constellations of the Zodiac? What is the right ascension of Leo, and when is Its centre on the meridian 7 When do the outlines of the figure come to the meridian ? What number of visible stars does It con tain, and how large ai« the principal ones ? What is the name of tho first star in tho eoDstellatlon, and whence is it derived? «Ul> IV. I ta^o. 79 It is situated almost exactly in the ecliptic, and may be readily distinguished on account of its superior brilliancy. It is the largest and lowest of a groUp of fire or six bright stars which form a figure somewhat resembling a sickle, in the neck and shoulder of the Lion. There is a little star of die 5th magnitude about 2° S. of it, and one of the 3d mag- nitude 6° N. of it, which will serve to point it out. Regius is the brightest star in the constellation, except Denebola, in the tail, 25*^ E. of it. Great use is made of Re- gulus by nautical men, for determining their longitude at sea* Its latitude, or distance from the ecliptic, is less than ^°; but its declination, or. distance from the equinoctial is nearly 13^ N. ; so that its meridian altitude will be just equal to that of the sUn on the 19th of Au^st. Its right ascension is very nearly 150°. It therefore culminates about 9 oc ock on the 6th of April. When Regulus is on the mefUlian, Castor and Fulhix are seen about 40^ N. W. of it, and the two stars in the Little Dog, are about the same distance in a 8 W. direction ; witli which, and the two former, it makes a large isosceles tri* «ngle whose vertex is at Regtdus> The next considerable star, is 5° N. of Regulus, marked Eta, situated in the collar ; it is of between the 3d and 4th magnitudes, and, with Regulus, constitutes the handle of the sickle^ Those three or four stars of the 3d magnitude, N. and W. of Eta, arching round with the neck of the animal, de- scribe the blade. At Gieba, is a bright star of the 2d magnitude., situated in the shoulder, 4° in a N. E. durection from Eta, and may be easily distinguished by its being the brightest and middle one of the thiee stars lying in a semicircular form, curving towards the west j and it is the first in the blade of the sickle. Adhafera, is a star of the 3d magnitude, situated in the neck, 4® N. of Al Gieba, and mav be known by a very mi- nute star just below it. This is tne second star in the blade of the sickle. Ras al Asact, situated before the ear, is a star of the 3i or 4th magnimde, 6° W. of Adhafera, and is the third in the blade of the sickle. The next star, Epsilon, of the 9%me magnitude, situated in the head, is 2^° S. W. of Ras al Aiad, and a little within the curve of the sickle. About mid'^ray Describe the aitoatlon of Resnilus. What other stars serve to point it out 1 Wr-at ts its comparative brightness i what use is made of It in nautical astronomy? Vhat are Us latitude and declination 7 On what day will Regulus culminate at 9 o'c) Tck in the evening ? When i» it on the meridian, with xohat stars does it form a large uianerle, and in what direction are they from it? What are the name and position of the next eousideiable star in Its vicinity? What stars form the blade of the sickle? ^^here Is ▲I Gtein sitnaterl, and how may it be distinguished? What is the poslUonof Adna»». and how may it be known? Describe the situation of Ras al Asad. h 80 PlCTUilK or TUE HEAVENS. [ APRIL between these, and a little to the £*, is a very small star hardly visible to the naked eye. S^ Lambda^ situated in the moutn, is a star of the 4th magni- tude, 3^0 S. W. of Epsilon, and the ^ast in the sickle's point. Kappa, situated in the nose, is another star of the same magnitude, and about as far from Lambda as Epsilon. Epsilon and Kappa are about 5^^ apart, and form the longest side of a triangle, whose vertex is m Kappa. ZozmcL, situated in the back of the Lion, is a star of the 2d magnitude, 18<^ N. E. of Reffulus, and midway between it and Coma Berenices, a fine cluster of small stars, IS^' N. E. of Zozma. Hieta, situated in the thigh, is another star of the 3d mag* nitude, 5^ directly S. of Zozma, and so nearly on the same meridian that it culminates but one minute after it. This star makes a right angled triangle with Zozma on the N. and Denebola on the E.^ the right an^le being at Theta. Nearly in a straight line with Zozma, and Theta, and south of them, are three or four smaller stars, 4° or 5*^ apart, which mark one of the legs. Denebola, is a bright star of the 1st magnitude, in the brush of the tail, 10° S. E.- of Zozma, and may be distin- guished by its great brilliancy. It is 5<^ W. of tne equinoc* tial colure, and comes to the meridian 1 hour and 41 minutes after Regulus, on the 3d of May ; when its meridian altitude is the same as the sun's at 12 o'clock the next day. Wlien Denebola is on the meridian, Regulus is seen 25<^ W. of it, and Fhad, in the square of Ursa Major, bears 39^ N. of it. It forms, with these two, a large right angled triangle ; the right angle being at Denelrala. It is su nearly on the same meridian with Pb^^ that it culminates only four minutes before it Denebola is 35^° W. of Arcturus, and about the same dis- tance N. W. of Spica yirginis, and forms, with them, a large equilateral triangle on the S. E. It al^o forms with Arcturus and Cor Caroli a similar figure, nearly as large on the N. E. These two triangles, being joined at their base, constitute a perfect geometrical figure of the forms of a Rhom- bus : called oy some, the Diamond op Virgo. A line drawn from Denebola through Regulus, and continued 7^ or 8° further In the same direction, will point out JEt and Oimcron^ of the 3d and 4th magni* tudes, situated in the fore claws, and about 3<^ apart. * What star is next? Describe the position of Lambda? Wbat are the sltujuton antf magnitude of Kappa? What is the distance between Epsilon and KappaT Describe the portion of Zozma? Wliat are the magnitude and position of 'Fheta? What geometri- cal figure may be formed with this star, Zozma and Denebola? What stars in thi« nelglu>ourhood mark one of the less of Leo? Describe Denebola? How fiur is It fVom the equinocttal colure, and when does it come to the meridian? When Denebola U en the meridian, what geometrical Jlgure does it form, in connexion with Reguhut and Phad 7 With what other star ie it nearly on the same meridian 7 What is the poviUon of Denebola in regani to Arctmrus and Spica Virglnis, and what figure does it fioim with them ? With what other stars does Denebola fonn a similar figure ? What lain 5eometrica' figure is formed by these two Niangles? What stars pomt out ffiou in Mi >re claws 7 MAP iY.| u:o. 81 There are a number of other starg of the 3(1 and 4th magnitudea In thia con- ttellation, which require no description, as the scholar wilt easily trace them out from the map. The position pf Rcgulus and Denebola are often referred to in the geography of the heavens, as tliey serve to point out otlkcr clusters in the same neighbourhood. ..j[^ History.— Accordinyto Greek fable, this Lion represents the formidable ani Dial which infested the forests of Neuuea. It was slain by Hercules, and placed by Jupiter among the stars in-commcmoration of the dreadful conflict. Some writers have applied the story of tlie twelve labours of lIercuIes«U) the procress of the sun through the twelve signs of the ecliptic ; and as the combat of that celebrated hero with the Lion was his first labour, they have placed Leo as ths Ant sign. The figure of the Lion wa& however, on the Egyptian charts long before the invention of the fables of Hercules. It would seein, moreover, ac* cording to the fable itsellj that Hercules, who represented the sun, actually slew the Nemaean Lion, because IjCo was already a zodiacal sign. In hierugiypliical writing, tlie Lion was an emblem of violence and fury ; and the re])resentation of this animal in the Zodiac, signified tlie intense lieat occa- sioned by the sun when it entered that part of the ecliptic. The Egyptians wer much annoyed by lions during the heat of summer, as they at tliat season, lei. the desert, and hunted tlic banlts of the Nile, which had then reached its greatest elevation. It was therefore natural for their astronomers to place the Lion where we find liim in the zodiac. The figure of Leo, very much as we now have it, is in all the Indian and ^m> tian Zodiacs. The overflowing of the Nile, which was regularly and anxiouay expected every year by the Egyptians, toolc place when the sun was in this sign. They therefore paid more attention to it, it is to be presuuied, than to any other. This was the principal reason. Mr. Green supposes, why Leo stands first in the KOfiiacs of Dendera. The circular ssodiac, mentioned in our account of Aries, and which adorned the ceiling in one of the inner rooms in the famous temple in that city, was brought away en masse in 1821, and removed to Paris. On its arrival at the Ix>uvre, it was purchased by the Icing for 150,000 francs, and, after being exhibited there for ^year, was placed in one of the halls of the library, where it is now to be seen m apparently perfect preservation. This most interesting relic of astrology, after bem^ cut away from the ruins where it was found, is about one foot thick, and eight feet square. The rock of which it is composetl, is sandstone. ^ On the face of this stone, appears a large square, enclosing a circle four feet in diame- ter, in which are arranged in an irregular spiral line, the zodiacal constellations, commencing with the sign Leo. On each side of this spiral line are placed a great variety of figures. These are supposed to represent other constellations, though they bear no analogy, in form, to those which we now have«. Many of^ thesi figures are accompanied witli hieroglyphics, whicti probably express tneir names. The commentator of Champollion, finom whom we have derived manr interesting facts in relation to them, has furnished merely a general history of their origin and purpose, but does not add particulars. Copies of these drawings and characters, have been exhibhed in this country, and the wonderful conclu- sions that have been drawn from them, have excited much astonishment. Compared with our present planispheres, or vrith stellar phenomena, it abonnds with coiuradictory and irrelevant mfltter. So far from proving what was strenu- msly maintained by infiiiel writers, soon afler its discovery, that the Greeks took from it the model of their zodiac, which they have transmitted to us, it seems to demonstrate directly the reverse. The twelve signs, it is true, are ther^ but they are not in their proper places. Cancer is between Leo and the pole ; Virgo bears no proimrtion to the rest ; some of the signs are placed double : they are all out of the ecliptic, and by no means occupy those regular and equal portion» diac, was used for the purposes of judicial astrolo^, and, tliat the sculptured figures upon it were employed in horoscopical predictions, and in that castimc of nativities for which the Egyptians were so famous. Whv U the poeUion t^Regulus and Denebola often referred to 7 8i riUTUKE OK THE HEAVENS. {.''^PRIL. In the Hebrew Zodiac, Leo is aesiffned to Judvh, on «rhopj standard, according lo all traditions, a Lion is painted. Tliis is clearl^r intimated in numerous passap ges of the Hebrew writings : Ex. — '^ Judah is a Lion's whelp ; he stoopeth down ne croucheth as a Lion ; and as an old Lion ; who shall rouse him up V Geu. zitx. 9. "Tlie Lion of the tribe of Judah hath prevailed." Rev. v. 5. LEO MINOR. The Little Lion. — This constellation was formed by Hevelius, out of the StellcB infonnes^ or unformed stars oi the ancients, which lay scattered between the Zodiacal con- stellation Leo, on the S. and Ursa Major, on the N. Its mean right ascension is the same with that of Regulas, and it comes to the meridian at the same time on the 6th of April. Tlie modem constellations, or those which have been added to our celestial maps since the adoption of the Greek notation, in 1603, are referred to by the letters of the English alphabet, instead of the Greek. This is the case in regard to Leo Minor, and all other constellations whose origin is subsequent to that period. Leo. Minor contains 53 stars, including only one of the 3d magnitude, and 5 of the 4tli. The principal star is situated in the body of the animal, 13° N. of Gamma Leonis,* in a straight line with Phad, and may be known by a group of smaller stars, a little above it on tne N. W. It forms an eqnllateral triangle with Gamma and Delta Leonis, the vertex being in Leo Minor. This star is marked with the letter /, in modem catalogues, and being the principal representative of the constellation, is itself sometimes called tJfe LitUe Li'>n ■ S° E. of this star (the Little Lion) are two stars of the 4th mag* nitude, m die last paw of Ursa Major, and about 10° N. W. of it, are two other of the 3d magnitude, in the first hind paw. ''The Smaller Lion now succeeds ; a cohort Of fifty stars attend his steps ; And /Aree, to sight unarm'd, invisible." SEXTANS. Tbe Sextant, called also Urania's Sextant,! is a modem constellation that Hevelius made out of the unformed stars of the ancients, which lay scattered between the Lion, on the N., and Hydra, on the S. It con tarns 41 very small stars, including only one as large * Leanit is the genitive, or possessive case of Leo, and Canima Leonis means rho Gamma of Leo. Thus also the principal star in Aries is marked AIp?M Arietigt meaO' log ttie Alpha of Aries, &c. ^ Urania was one of the muses, and daughter of Jupiter and Mnemosyne. She pre- sided over astronomy. She was represented as a younir vlrfrln, dressed In an azure- coloured robe, crowned with stars, holding a robe in her hands, and having many mathematical instruments about her. What is the oripln of Leo Minor, and how Is it slmated? What Is Its mean right as- censloni When is It on the meridian) What are the number and magnitude of Its sUiTS? What is the position of the principal star in this constellation, and how may It be known ) Whatjlsrure dont it form with seme other start f HTrat letter represents Ms-flttr, and what else is it eaHeel 1 What nehvltf do we Jltid in this cottsteBaMon 7 What are tlie origin and position of the Sextant ? How many stars does It contain > HAP fV.j HYDRA AND THE CUP. 83 9s the 4th magnitude. This is situated very near the equi- noctial, 13^ S. uf Regulus, and comes to the meridian about the same time on the 6th of April. The other stars in this constellation are too small to engage attention. A few of the largest of them may be traced out from the map. HisToipr. — ^A sextant, in mathematics, la the sixth part of a circle, or an arch comprehending 60 dej^rcea. Bat the tertu is more particularly used to denote an astronomical instrument well known to mariners. Its use is the same as that of the quadrant: namely, to measure the angular distance, and take the altitude «:f the sun, moon, planets, and fixed stars. It is indispensable to the mariner in finding the latitude and longitude at sea, and should be in the hands of every surveyor and practical engineer. It may serve the purpose of a theodolite, m measuring inaccessible heights and distances. It maj gratify the young pupil to know, that by means of such an instrument, well adjusted, and with a clear eye and a steady hand, he could readily tell, within a few hundred yards, how &r north or south of the equator he was, and that from any quarter of the world. Known or unknown. This constellation is so called, on account of a supposed resemblance to tills instrument. HYDRA AND THE CUP. Hydra, the Water Serpent, is an extensive constella- tion, winding from E. to W. in a serpentine direction, over a space of more than 100 degrees in length. It lies south of Cancer, Leo, and Virgo, and reaches almost from Canis Mi nor to Libra. It contains sixty stars, including one of the 2d magnitude, three of the 3d, and twelve of the 4th. Alphard, or Cor Hydrce, in the heart, is a lonctstar of the 2d magnitude, 23° S. S. W. of Regulus, and comes to the meridian at the same tfme with Lambda, in the point of the sickle, about 20 minutes before 9 o'clock on the Ist of April. There is no othet considerable star near it, for which it can be mistaken. An imaginary line drawn from Gamma Leonis through Regulus. will point out Cor Hydrae, at the distance of 23°. The head of Hydra may be distinguished by means of four stars of the 4th magnitude, 2^° and 4° apart, situated 6^ S. of Acubens, and forming a rhomboidal figure. The three upper stars in this cluster, form a small arch, and may be known by two very small stars lust below the middle one, making witn it a very small triangle. The three western stars in the head, also make a beautiful little triangle. The eastern star in this group, marked Zeta, is about 6^ directly S. of Acubens, and culminates at the same time. When Alphard is on the meridian, AlkeSy of the 4th mag« nitude, situated in the bottom of the Cup, may be seen 24<> \* What is the position of the laxsest one? Describe the situation and extent of the constellation Hydra. What are tne number and magnitude of its stars 7 Describe the positton and magnitude of Alphaid. What are the distance and direction 9{,cor Hy. i5» ftwn Gamma Leonis 7 How may the head of Hydra be dlstingulahe'l ? How m«r the three imper stars in this cluster be known? Which stars form a beauunu uni» ttiaiigiel mm is Alkes situated, and when may it be seem 84 PICTURE OF THE HEAVENS. | AKKIL- S. E.-of itj and is distin^ished by its forming an eqailateral triangle with Beta and Gamma, stacs of the same magnitude, 6^ S. and E. of it. Alkes is common both to Hydra and the Cup. Beta, on the S., is in Hydra, and Gamma, on the N. E., is near the middle of the Cup. A line drawn from Zozma, through Theta Leonis, and continued 3S^^ directly S. will reach Beta; it is therefore on the same meridian, and will culminate at the same time on the 23d of April. The Cup itself, called also the Crater^ may be easily dis- tinguished by means of six stars of the 4th magnitude, form- ing a beautiful crescent, or semicircle, opening to the W. The centre of this g^roup is about 15° below the equinoctial, and directly S. of the hinder feet of Leo. The crescent form of the stsurs in the Cup is so striking and well defined, when the moon iV absent, that no other description is necessary to point them oiHk Its centre comes to the meridian about two hours after AlpKard, on the same evening; and consequently, it culminates at 9 o'clock, one month after Alphard does. The remainder of the stars in this constellation may be easily traced by aid of the map. When the head of Hydra is on the meridian, its other ex- tremity is many degrees below the horizon, so that its whole length cannot be traced out in the heavens until its centre, or the Cup, is on the meridian. \ " Near the equator rolls The sparkling Hvdra, proudly emment To drink the Galaxy s refulgent sea ; Nearly a fourth of the encircling curve Which girds tlie ecliptic, his vast folds involve ; , Yet ten the number of his stars diffused '^er the long track of his enormous spires : Cmc/* beams his heart, sure of the second rank, But emulous to gain the first." — Eudosia. Hi8T The Great Bear. — This great constellation is situated Detween Ursa Minor on the north, and Leo Minor on the south. It is one of the most noted and conspieuous in the northern hemisphere. It has heen an ohject of universal ob- servation in all ages of the world. The priests of Belus, and the Magi of Persia ; the shepherds of Chaldea, and the rhqe- nician navi^tors, seem to have been equally struck with its peculiar outlines. And it is somewhat remarkable that a re- mote nation of American aboris^ines, the Iroquois, and the earliest Arabs of Asia, should nave given to the very same constellation the name of " Great Bear," when there had probably never been any communication between them ; and when the name itself is so perfectly arbitrary, there being no resemblance whatever to a bear, or to any other animal. It is readily distinguished from all others by means of a remarkable cluster of seven bright stars, forming what is familiarly termed the Dipper, or Ladle. In some parts of England it is called " Charles's Wain," or wagon, from its fancied resemblance to a wagon drawn by three horses in a line. Others call it the Plough, The cluster, however, is more frequently put for the whole constellation, and called, simply, the Great Bear. But we see no reason to reject the How is Ursa Major situated 1 How has it always been reeaxdedi What pet^le seem to have been peculiarly sttuck with its splendour? what remaTkabie dr* cumstance respecting Its name? Is there any resemblance between the outUnes of this constellation and the figure of a bear? By what is this constellation reoouy ois- tingxdshed ftam all others ? By what other names is the Dipper called i whnt u uus cluster mors ftequently calle4i o 66 PICTDBE OF THfi SKAVENS. Lmay. \ rery appropriate appellation of the shepherds, for the resem- blance IS certainly in favour of the Dipper : the four stars in the square forming the bowl, and the other three, the handle. When the Dipper is on the meridian, above the pole, the bottom lies towards us, with the handle on the right. Benetnasch is a bright star of the 2d magnitude, and is the first in the handle. The second, or middle star in the handle, is Mizar, 7° distant from Benetnasch. It may be known by means of a very minute star almost touching it, called Alcor^ which appears to be double when seen through a telescope, and of a silver white. The third star in the handle is called Alioth^ and is about 4 Jo W. of Mizar. Alioth is very nearly opposite Shedir in Cassiopeia, and at.au equal distance from the pole. Benetnasch, Mizar, and Alioth, constitute the han- dle, while the next four in the .square form the bowl of the Dipper. Five and a half degrees W. of Alioth is the first $tar in the toj) of the Dipper, at the junction of the handle, called Megrez ; it is the smallest and middle one of thb cluster^ and is used in various observations both on sea and land, for important purposes.* At the distance of 44° S. W. of Megrez, is Phad, the first star in that part of the bottom, which is next the handle. The stars ia this cluster are so well known, and may be so easily described without reference to their relative bearings, that they would rather confuse than assist the student, were they given with ever so much accuracy. The several bearings for this cluster were taken when Megrez was on the meridian, and will not apply at any other time, though their respective distances vrill remain the same. At the distance of S^ W. of Phad, is- the westernmost star in the bottom of the Dipper, called Merak. The bright star 6° N. of itj towards the pole, is called Dubhe : but these two. Merak and Dubhe, are, by common consent, ^called the Point- ers, because they always point towards the pole ; for, let the line which joins them be continued in the same direction 28^^ farther, it will just reach the north pole. The names, positions, and relative distances of tlie stars in this cluster, should be well remembered, as they will be fre- * "When Megrez and Caph have the feame altitude, and arc seen in the same boil Kontal line east and west, the polar star Is then at itMreatest elongation Arom the true pole of the heavens ; and this Is the proper time for an observer to take its angle of elevation, in oider to determine the latitude, and Its azimuth or angle of declination, in Older to determine the magnetic variation. What, on the whole, is an appropriate appellation for It, and why? ncscrihc the po- sition of the Dipper when on the meridian. Describe the position of Benetnasch. Wfiat Is the next star In the Dipper, and how may It be known) What is the next, or tfaiid star In the Dipper? What stars form the bowl and handle of the Dipper? Describe tin position and use of Megrez. What star Is situated next to Mefrrez i Descrf*^ the po- sition of Merak and Dubhe. What ax« these stars called, and whv } ItAf VI. "l CRdA MAJOR. 87 quently adverted to. The distance of Dubhe, or the Pointer oearesr to the north pole, is 28}*^. The distance between tlie two upper stars in the Dipper is 10*^ ; between the two lower ones is 8^ : the distance from the brim to the bottom next the handle, i& 4^° ; between Megrez and Alioth is 5^° ; between Alioth and Mizar 4^^, and between Mizar and Benetnasch, 7^ The reason why it is important to have these distances clearly settled in tba mind is, that these stars, being always in view, and more familiar than any other, the student will never fail to have a standard measure before him, which the eyo can easUy make use of in determming the distances between other stars. The position df Megrez in Ursa Major, and of Caph in Cassiopeia, is somewhat remarkable. They are both in the eqainoctial dolure, almost exactly opposite each other, and equally distant from the pole. Caph is in the colure, which passes through the vernal equinox, and Megrez is in that which passes through the autumnal equinox. The latter passes tne meridian at 9 o'clock, on the 10th of May, and the former just six months afterwards, at the same hour, on the 10th of November. Psi, in the left leg of Ursa Major, is a star of the 3d mag- nitude, in a straight line wllh Megrez and Phad, distant from the latter 12^^. A little out of the sam^line, 3° faijther, is another star of the 3d magnitude, marked Epsilon^ which may be distinguished from Psi, from its forming a straight line with the two Pointers. The right ibre paw, and the two hinder ones, each about 15° from the other, are several y distinguished by two stars of the 4th magnitude, betweea_lo and 2° apart. These three duplicate stars are nearly in a right line, 20® S. of, and in a direction nearly parallel with, Phad and Dubhe. and are the only stars in this constellation that ever set in tnis latitude. There are few other stars of equal brightness with those just described, but amidst the more splendid and interesting group with which they are clustered, they seldom engage our observation. The whole number of visible stars in this constellation is 87 ; of which one is of the 1st, three are of the ^d, seven of the Sd*, and about twice as m^ttty^ of the 4th magnitude. HifTost.— UiusA Major is said to be Calisto, or Helicei daugbtMT of Lycaon, What is the distance of DUbhe fh>m the north pole 7 Mention the relative distances between the other stars in this group. Why U it important to have the relative dit' tmteeg qftheue g^^rafrom each (aher weU settled in the mind 7 What is there remark- able in the poaiti % of Megrez, and Caph in Casstopelal When do they pass the moo lUian? De8crtt)t he position of Psi. Where Is iSpsilon situated, and how may ii be distinguished? Rv ▼ are the paws of the Bear distinguished) What is the sluiaUoa «f these stars with t^ «pect to Phad and Dubhe » What are the only stars In this con^ fltellaUon that ever se In this laUtudel What Is the whole number of yisible ataxa la tbis conaiBUation, am. iw many of each magnitude * l«ir 1 Unl nl ftrudiL Shewu uiitteiiikiitoriHuit,' ud ouUicI oTAreM, bj Jo- pilcr, wlio placed her auioag iba conaleUuiaaa, tltei Ibe Jetioug; gf Jimohad Bwunf ]ker ([> «anll, uid dragged ber on Lhe ground i Her umB graw fihaggy uid de^Im'd wilh hwr, BernaJEB are ahuueo*d iiiEo poioLed cIawh, Her hands beu hdTber weight, and tunt la pttn; Her lipa,lhu once cauM lemplaiod, be(ia To grow diaoned in ui uglj grin : And lew [he suppUcUInf brule mlihl regch The un of Jove, she wu ile|wi>ed of ipeech. How did she fear to lodge Id wooda alone, And haunt the fleltb and meadows, once her owa F Bow often woutd the deen-mouih'd doga puiaue, Borne auppose thai her &oa Arcaa, utherwitE catLed Bootea. wad chanfvd Iuia Una Minor, or the Liide Beu. It ii well koown, thai ihe ancients repreieuled hence Ihe ippelteUon of darffi's Vat'ii, oc naaon. Thia la alluded ta in th* FhenomenAorAiaIua,aGreekpoeiii, from which St. Paul quotea. in hia addreaa "The une caU'd Helli,! aoon as daj relirai, Obaerredwllb ease, Ufhls qp hli radiant Drea; ■ Diana was Ute eodd«a nr hunUog, and the pUdnau tt modtitiF anit chaaUij i— Haile llie aacrlllce t iV.J COMA BEREKtCCIU BC The other, smaner, and with feebler besnui) lo a less circle drives its lazy teams ; Bnt more adapted for the sailor's guide, Whene'er, by night, he tempts the briny tide." In Che Egypdan planispheres of remote antiquity, these two constellations are represented by the figures of bears, instead of wagons ; and the Oreeka, who derived most of their astronomical symbols from the Egyptians, though they usually altered them to emblems of their own history or superstitK>n, have, nev* erthcless, retained the original form of the two bears. It is said by Aratus, that the Phenician navigators made use of Ursa Minor in directing their voyages :•— "Observing this, Pheniciana plough the main :" while the Greeks confined their observations to Ursa Major. Some imagine tliat the ancient £syptians arranged the stars near the north pole, within the outlines of a bear, becanae the polar re^ons are the haunts of this animal, and also becaose it makes neither extensive journeys nor rapid •narches. At what period men began to sail by the stars, or who were the first people ihfltf did so, is not clear ; but the honour is usually given to the Pheniciana. That It was practised by the Greeks, as early as the time of the Trojan war, that il^ about 1200 years B. C, we learn from Homer ; for he says of Ulysses, when sailing on his ra^ft, that " Placed at the helm he sate, and mark'd the skies^ Nor closed in sleep his ever watchful eyes." It is rational to suppose that the stars were first used as a guide to travelleni by land, for we can scarcely imagine that men would venture themselves upon the sea by night, before they had first learned some safe and sure methoa of directing their course by land. And we find, accordii^ to Diodorus Biculus, that travellers in the sandy plains of Arabia were accustomed to direct their course by the Bears. That people travelled in these vast deserts at night by observing the stars, is directly proved bv this passage of the Koran : — " God lias given you the star* to be guides in the curk. both by land and by sea." COMA BERENICES. ' Berenice's Hair. — This is a beautiful cluster of small stars, situated about 5^ E. of the equinoctial colure, and mid- way between Cor Caroli on the northeast, and Denebola on the southwest. If a straight line be drawn from Benetnasch through Cor Caroli, and produced to Denebola, it will pass through it. The principal stars are of between the 4th and 5th magni- tudes. According to Flamsted, there are thirteen of the 4th magnitude, and according to others there are seven ; but the student will find a^eeably to his map, that there is apparently but one star in this group, entitled to that rank, and this is situated about 7^ S. E. ol the main cluster. Although it is not easy to mistake this group for any other in the same region of the skies, yet the stars, which compose it are all so small as to be rarely distinguished in the full pre- sence of the moon. The confused lustre of thii assemblage Describe the appeanuioe and situation of Coma Berenices. What are the magnitudes a the principal stars In this cluster? What are they, according to Flamsted and "nhers 7 How many stars of the 4th magnitude will the student And on the map 7 Is It tasy to mistake this group, and Is it visible In presence of the moon 7 8* PlCTtJB& or TBE H£AV£MS. 1^^^- of small stars somewhat resembles that of the Milkr-Way . ft contains besides the stars already alluded to, a number of nebulae: The whole number of stars in this constellatioil is 43 ; its mean right ascension is 185^. It consequently is on the me* rjdian the 13th of May. « Now behold The glittering maze of Bereniee'e Hair ; Forty the starB ; but sueh as seem to kiss The j2otrt>i^ tr^aet with a lambent fire : Four to the telescope alone are seen." History.— Berenice was of royal descent, and a lady of great beautyi who married Ptolemy Soter, or Eveiigetes. one of the kings of E^rpt, her own bro- ther, Tvhom she loved with much tenderness. Whenlie was going on a danger* ous expedition against the Assyrians, she vowed to dedicate her hair to the goddess of beauty, if he returned in safety. Sometime after the victorious re> turn of her husband, Evervetes, the locks which agreeably to her oath, she had deposited in the temple of Venus disajppeared. Tne king expressed great re- gret at the loss of what he so much prized ; whereupon Conon, his astronomer, publicly reported that Jupiter had taken away the queen's locks finom the temple, and placed them among the stars. " There Berenice^a locks first rose so bright, The heavens bespangling with dishevelled light" Conon. beinff sent for by the king, pointed out this constellation, saying. "There Dehoid the locks of the queen." This group being among the unformed flters until that time, and not known as a constellation, the king was satisfied with the declaration of the astronomer, and the queen became reconciled to the par^ tiality of the gods. Callimachus, an historian and poet who flourished long before the Christiaa era, has these hues as translated by Tytler : — *' Immortal Conon, blest with skill divine, A.mid the sacred skies behold me shine ; E'en me, the beauteotu Aatr, that latelv shed Refulgent beams from Bererace'e head ; The lock she fondly vowed with lifted arms, Imploring all the powers to save from harms Her dearer lord, when from his bride he flew, To wrec)c stem vengeance on the Assyrian crew." \ CORVUS. The Crow. — This small constellation is situated on the eastern part of Hydra, 15° E. of the Cup, and is on the same meridian with Coma Bej*enices, but as far S. of the equinoc- tial as Coma Berenices is N. of it. It therefore culminates at the same time, on the 12th of May. It contains nine yisi- ble stars, including three of the 3d magnitude and two of the 4th. This constellation is readily distinguished by means of three stars of the 3d magnitude and one of the 4th, forming a trapezium or irregular square, the two upper oires being about 3^° apart, and the two lower ones 6° apart. What does its lustre resemble? What is the number of Ktars in this constellation, and when is It on the meridian? Where is the Crow situated? When ts It on th^s ra»> Hdlan? What are the number and magnitude of its stars f How is it readily distlii' «ul»becir UAI* IV. j COBVUflt 91 The brightest of the two upper stars, on the left, is called Algorab, and is situated in the E. wing of the Crow ; it has nearly the same declination S. that the Dog-star hasj and is OB the meridian about the l3th of May. It is 2H° E. of Alkes in the Cup, 14^° S. W. of Spica Virginis, a brilliant star of the 1st magnitude to be described in the next chapter* Betu^ on the back of Hydra and in the foot of the Crow, is a star of the 3d magnitude, nearly 7^ S. of Al^orab. It is the brightest of the two lower stars, and on the left. The right- hand lower one is a star of the 4th magnitude, situated in the neck, marked Epsilon, about 6^ W. of Beta, and may be known by a star of the same magnitude situated 2° below it, in the eye, and called Al Chiba. Epsilon is 21f ° S. of the Temal equinox, and if a meridian should be drawn from the pole through Megrez, and produced to Epsilon Corvi, it would mark the equinoctial colure. Gamma in the W. wing, is a star of the 3d magnitude, 3^^ W. of Algorab, and is the upper righthand one in the square* It is but 1^ E. of the equinoctial colure. 10^ E. of Beta is a star of the 3d magnitude, in the tail of Hydra, marked Gamma; these two, with Algorab, form nearly a right angled triangle, the right angle being at Beta. History. — ^The Crow, it is said, was once of the purest white, but was changed for tale-bearing to its present colonr. A fit punishment for such a fvaXi I **The raven once in snowy plumes was drest, White as the whitest dove's unsullied breast, Fair as the guardian of the capitol, Soil as the nwan ; a large and lovely fowl ; His tongue, his prating tongue, had changed him quite, To sooty blackness from the purest white." According to Greek fable, the Crow was made a constellation by Apollo. This god being jealous of Coronis. (whom he tenderly loved,) the daughter of Phie- gyas and mother of OSsculapius, sent a crow to watch her behaviour ; the bird perceived her criminal partiality for Ischys the Thessalian, and immediately acquainted Apollo with her conduct, which so fired his indignation that he lodged in arrow in her breast, and killed her instantly. ''The god was wroth ; the colour left his look, The wreath his hea4 the harp his hand forsook; His silver bow and feather'd shafls he took, And lodged an arrow in the tender breast. That had so often to his own been prest." To reward the crow, he placed her among the constellations. Others say that this constellation takes its name from the daughter of Coro* naeus, king of Phocis, who was transformed into a crow by MineIV^^ to rescue the maid irom the pursuit of Neptune.' The following, from an eminent Latin poet of tlie Augustine age, is her own account of the metamorphosis as transla^ ted into English verse by Mr. Addison : — * For as my arms I lifted to the skies, I saw black feathers from my fingers rise: Describe the position of Algorab. How does its declination compare with that ni Blrius? What are ite distance and direction ftom Alkes and Bplca Virginis? De- scribe the situation of Beta. Describe ihc situation of the righthand lower star, what Is tbo distance of Epsilon from the vernal equinox, and how may the «q"ipocY« colnxe be tnwed out by U7 What are the roagnltade and poslUon of Gamma? Of Beta} M PICTCA« OP THS BEAVEN8. |bUT t strove to flinf my icuinent on the |[roimd ; My garment turned to plumee, and girt me round : My Hands to beat my naked bosom trvj Nor naked bosom now nor )iand8 had I : . Lightly I tripp'd, nor weary as before ^ Bunk m the sand, but skimm'd along the shore ; Till, rising on my wings, I was preferred Tb be the chaste Minerva's virgin bird." \ VIRGO. The Virgin. — This is the sixth si^n, and seventh constel* lation in the ecliptic. It is situated next east of Leo, and about midway betw^een Coma Berenices on the N. and Cor- vus on the S. It occupies a considerable space in the hea- vens, and contains, according to Flamsted, one hundred and ten stars, including one of the 1st, six of the 3d. and ten ot the 4th magnitudes. Its mean declination is 5^ N., and its mean right ascension is 195^. Its centre is therefore on the meridian about the 23d of May. The sun enters the sign Virgo, on the 23d of August, but does not enter the Goi^telUUion before the 16th of September. When the sun is in this sign, the earth is in Pisces ; and vice versa. Spica Virginia, in the ear of com* which the virgin holds in her left hand, is the most brilliant star in this constella- tion, and situated nearly 15° E. N. E. of Algorab in the Crow, about 35° S. E. of Denebola, and nearly as far S. S. W. of Arcturus — three very brilliant stars of the 1st magnitude that form a large equilateral triangle, pointing to the S. Arc- turns and Denebola are also the base of a similar triangle on the north, terminating in Cor Caroli, which, joined to t!ie former, constitutes the Diamond of Virgo. The length of this figure, from Cor Caroli on the north to Spica Virginis on the south, is 50<=>. Its breadth, or shorter diameter, extending from Arcturus on the east, to Denebola on the w^st, is 35Jf°. Spica may otherwise be known by its solitary splendour, there being DO visible star near it except one of the 4th magnitude, situ- ated about 1° below it, on the left. The position of this star in the heavens, has been deter- mined with great exactness for the benefit of navigators. It « In the Egyptian Zodiac, Isis, whose place was supplied by Virgo, was represented with three ears of com in her hand. According to the Egyptian mythology, Isis was said to have dropped a sheaf of com, as she fled from Typhon, who, as he continued to pursue her, scattered it over the heaven . The Chinese call the Zodiac the ytilow road, as resembling a path over which the ripened ears of com are scattered. What Is the relative position of Virgo among the signs and constellations of the ecliptic? How U it situated } How many stars does it contain, and how large are the principal ones? What are its mean declination and right ascension? When is the centre of the constellation on the meridian? Descrll)e the principal star In Vlxgo. What are the distance and direction of Virgo from Algorab, penebola and Arcmrus? What axe the mafnltude and appearance of these three stars, and what figure do they form? Row may Spica l>e otherwise distinguished? Why has Its position been doteimhiOd with great exactness | « H4P IV.J VIRGO. 93 IS one of the stars from which the moon's distance is taken for determining the longitude at sea. Its situation is highly faYOurahle for this purpose, as it lies within the moon's path, and little more than 2° below the earth's orbit. Its risht ascension bein^ 199<>, it will come to our meridian at 9 o'clock about the 28th of May, in that point of the heav- ens where the sun is at noon about the 20*h of October. VindemiatriXf is a star of the 3d magnitade, in the right arm, or northern wing of Virgo, and is situated nearly in a straixht line with, and midway between Ooraa Berenices, and Spica Vii^^nia. It is I9jk° S. W. of Arctorus, and about the same distance S. £. of Coma Berenices, and forms with these two a large bri- angle, pointing to the sooth. It bears also 18° S. S. E. of Dcnebola, and cornea to the meridiaji about 23 minutes before Spica Viiginis. Ze/a, is a star of the 3d magnitude 11^° N. of SjHca, and very near the equi- noctiaL Gamnutf situated near the left side, is also a star of the 3d magnitude} and very near the equinoctiaL It is 13° due west of Zeta, with which and Spica it forms a handsome triangle. EtOy is a star of the 3d magnitude, in the southern wing, 5P W. of Osunma, and but 2^° £. of the autumnal equinox. Beta, called also ZavijavOj is a star of the 3d mfllgnitude, in the shoulder of the wing, 7^° W. of Eta, with which and Gamma, it forms a line near the Earth** orbit, and parallel to it Beta, Eta. Qamma and Spica, form the lower and longer nde of a large spherical triangle whose vertex is in Beta. The other stars in this figure may be easilv traced by means of the map. About V39 E. of Spies, thero are two stars of the 4th magnitude, 3° apart, which matk the foot of Viigo. These two stars are on nearly the same meridian with Arcturus, and culminate nearly at the same time. The lower one, marked Lambda^ is on the south, and but 8^ Vf. of the princi^ star in Libra. Several other stars of the 3d magni- tude lie scattered about in this constellation, and may be traced out by the ma|i. **Her lovely tresses glow with starry light ; Stazs ornament the bracelet on her hand ; Her vest in ample fold, glitters with stars : Beneath her snowy feet they shine ; her eyes Lighten, all glorious, with the heavenlv rays. But Jirst the star which crowns the golden sneaf.'* HisTOBT. — The lamous zodiac of Dendera, as we have already noticed, com* mences with the sign Leo ; but another zodiac, discovered among the ruins at Estne, in Egypt, commences with Virgo ; and from this circumstance, some have annied, that the regular precession of the equmozes established a date to thHi at least 2000 years older tnan that at Dendera. The discoveries of Cham* polljon, however, render it probable that this ancient relic of astrology at Estne was erected during the reign of the Emperor Claudius, and consequently did not precede the one at Dendera more than fourteen vears. Of this, however, we may be certain : the autunmal equinox now corresponds With the first degree of Virgo ; and, consequently, if we find a zodiac in which the summer solstice was placed where the autumnal equinox now is, that zodiac carries us back 90° on the ecliptic ; this divided by the annual precession 601^', must fix the date at about 6450 years ago. This computation, according to the chronology of the Sacred writings, carries us back to the earliest ages of the human species on earth, and proves, at least, that astronomy was among the first studies of mankind. The most rational way of accounting for this zodiac, says Jamieson, is to ascribe it to the fii.mily of Noah ; or perhaps to the patriarcn himself; who constructed it for the benefit of those who should live after the deluge, and who preserved it as a monument to perpetuate the actual state of the heavens immediately subsequent to the creation. Fable represents the ancient Egyptians as believing that the yearly and regu- lar inundations of the Nile proceeded from the abundant tears' which Isis shed _ I ■ J I I II ■ I I I ■ — "" Why is its situation favourable for taking the moon's distance 1 When does It pass oar meridian ? Describe the situation of Vindemiatrix. Describe the^gurewM^ U ibrms with other stars in the same netghbowrhood. What are its Mstanes and bearing ^omDtmeboiaJ Describe T^eta. Describe Gamma. Describe the position tfJXaD^ crfbe MsfOiftfOn qTBeta. What geometHcalMure may be farmed t^thettars in tim netghbotufHoedi deigned lo have been slain bj rbuH myibok^, Jn draci mbobcaf iBPpiagB which p phfSlcMl BlUe of the world. niTenled « inaiiimaie obi«iH ; and the pneslfl redu- lo feblei, which ihu people belleTed u condilion of mankind during lbe flisl agea "d wLtven, ar pair of K Joe (U preeente Ihe iligin A«- during (he goldan age ; nkindauringthebr^en ra"in''DDe bwduid a hQDund lean bejbre (ha binh of our lour igea of Ibo »i>rld| (be golden, the good: tfie'eKIh"£rmuM'Srlh'heTVnilU en cnnlinuallT qnarrelled wSh eath oUiet ; icmyand murder alalned (he hWOTTOf odB did not disduio 10 mil bmiliarly with known. But Ibii hp^ppj hu every day. In Lhe golden age. Ihe gods did (he sons of men. The lanocenoe, Ihe inlegrl., ._ . ..... found among uB, wore a pleating upeclacle even to superior nalurei ; bol u minkiod dBgeneraied, one god after analberdeserledlhelrlale beloved hauma ; Virgo. The dealh of her Falher IcarluB, an Alhenian, who pMished bj — hanili or >Dme peasanla. whom he hadlnloilcaled wiih wine, earned a (11 of despair, la which Erigone bung herself; and she was aflerwards, as II lsnl\ placed among Ihe signs of Ihe zodiac. She was directed by her lailhnil Op« hung herae^ I'i'eiJiiiig, she soughl a stronger, in order lo effect her purpoae. ''Thus ODce In Msralhon's Impervious wood, ETigoM beside her lather stood, ASTERION ET CHARA; VEL CANES VENATICL The GRBVHonnDs. — This raodeiD constellalion, embracing two in one, waa made by Herelius out of the onfonned stan MAP IV.1 BOOTES. 05 9f the ancients which were scattered between Bootes on the east^nd Ursa Major on the west, and between the handle of the Dipper on the north, and Coma Berenices on the south. These Hounds are represented on the celestial sphere as being in pursuit of the Great Bear, which Bootes is nuntin^ round the pole of heaven, while he holds in his hand the leash by which they are fastened together. The northern one is called AsterioTij and the southern one, Charcu The stars in this group are considerably scattered, and are principally of the 5th and 6th magnitudes ; of the twenty-five stars which it contains, there is but one sufficiently large to engage our attention. Cor Caroli, or Charleses Hearty so named by Sir Charles Scarborough, in memory of Kin«^ Charles the First, is a star of the 3d magnitude, m the necK of Chara the Southern Hound. When on the meridian, Cor Caroli is 17^° directly B. of Alioth, the fhird itar in the handle of the Dipper, and is so neaiiy on the same meridian that it culini* nates only one minute and a half after it. This occurs on tlie 20th of May. A line drawn from Cor Caroli through Alioth will lead to the N. polar star. Ttiis star may also be readily distinguished by its being in a straight line with, and midway between Benemasch, the first star in the handle of the Dipper, ana Coma Berenices : and also by the fact that when Cor Caroli is on the meridian, Denebola bears 28° S. W., and Arcturus 26<3 S. E. of it, forming with these two •tars a very large triangle, whose vertex is at the north ; it is also at the norths ern ejctremity of the lan^e Diamond, already described. The remaining stars in this constellation are too small, and too much suttertd to excite our interest CHAPTER VIII. DIBECTIONS FOR TRACRfG THE CONSTELLATIONS WHICH ARE ON THE MERIDIAN IN JUNE. BOOTES.* - The Bear-Driter is represented by the figure of a hunts- man in a running posture, grasping a club in his right hand, and holding up in his left the leash of his two greyhounds, Asterion and Chara, with which he seems to be pursuing the Great Bear round the pole of the heavens. He is thence called Arctophylax, or the " Bear-Driver." * Pronounced Bo-o'-tes. How are the Greyhounds represented? By what names are they distinguished? What are the magnitudes of the stars which compose this group, and how are they sit- uated with respect to each other? Describe the principal star. When on the meridian What i» its situation with regard to Alioth 7 Hoio i$ Cor Caroli situated with reapeet to the volar star ? How may this star he otherwise readily distinguished ? Whtu larf geonutriealJUntre does it firm with two other bright stars in Us vicinUy 7 How is tha bola? What remarkable amjlguration in this part of the sky 7 What is tiie distance of Arcturus from the earth, compared with that of the other stars in the northern hem- isphere 7 Whaz etarejlve or six degrees eouthwest of Arcturus ? What stars in Ote other lesrJ Describe the star Mirac. Describe Saimts. With what other stare does Seginus farm a right emffled triangle 7 Describe the position cf Alkaturops Dtseribm (he position vDwa. Describe Sekkar. -s-^ «• —w MAP IV. J BOOTES. 97 in the bandlo of tlie Dipper. About 6*^ E. of Benetnasch U another star of tha itli man^ttude, sitoatea in the arm, which formSi with Benetriamrh and the three in tlio hand, an equilateral triangle. The three stars in the left hand of Bootes, the first in the handle of the Dipper, Cor enroll, Coua Berenices, and Denebola, are all situated neaxiy in the same rig)it line, running from northeast to southwest. " Bootes follows with redundant light ; fHfty-four stars he l)oast8 ; one guards the BeaTj Tliencc call'd ArcturuSj of resplendent frf»nt, Tlie pride of the^r»/ order : eight are veil'd, Invisible to the unaided eye." Manilius thus speaks of this constellation :— "And next Bootes comes, whose ordered beams Present a fi^rure driving of his teams. Below his girdle, near his knees, he bears The bright ArcturuSj fairest of the stars." Arcturus is mentioned hy name in that beautiful passage in Job, already referred to, where the Almighty answers " out of the whirlwind," and says : — "Canst thou the sky's benevolence restrain, And cause the Pleiades to shine in vain 7 Or, when Orion sparkles ihxn his sphere,. Thaw the cold seasons and unbind the year 1 Bid Mazzaroth his station know, And teach the bright Arcturus where to glowl" Ymtng'a Paraphrcue. HiSTOBY. — The ancient Greeks called this constellation Lycaon — a name de> rived from Xvxof) which signifies a tcoif. The Hebrews called it Caleb Anubach, the " Barking Dog ;" wliile the Latins, among other namecL called it Canie. If we go back to the time when Taurus opened the year, and when Virgo was the fifth of the zodiacal signs, we shall find that brilliant star Arcturus, so remarka- ble for its red and fiery appearance, corresponding with a period of the year as remarkable for its heat Pythagonis, who introduced the true system of the universe into Greece, received it from CBnuphis, a priest of On, in Egypt. And this college of the priesthood was the noblest of the east, in cultivating the studies of philosophy and astronomy. Among the high honours which Pharaoh confer- red on Joseph, he very wisely gave him in marriage "a daughter of tlie priest of On." Tlie supposed era oi the book of Job, in which Arcturus is repeatedly mentioned, is 1513 B. C. Bootes is supposed by some to be Icarus, the father of Eri^one, who was killed by shepherds for intoxicating them. Others maintain that it is Ericthonius, the inventor of chariots. According to Grecian fable, as well as later authorities, Bootes was the son of Jupiter and Calisto, and named Areas. Ovid relates, that Jono, being incensed at Jupiter for his partiality to Calisto, changed her into a bear, and mat her son Areas, who became a famous hunter, one day ronsed n bear in the chase, and not knowing that it was his mother, was about to kill her, when Jupiter snatched them both up to heaven and placed them among the caa- stellationa. Met b. ii. v. 496-£0a "But now her son had fifteen simimers told, Fierce at the chase, and m the forest bold ; When as he beat the woods in quest of prey, - He chanced to rouse his mother where she laf . She knew her son, and kept him in her sight. And fondly gazed : the boy was in a fright. And aim'd a pointed arrow at her breast ; And would have slain his mother in the beast ; But Jove forbad, and snatch'd them through the air In whirlwinds up to heaven, and fix'd 'em there ; Mfuertbe the ihru$tar» in the teftJumd ofBootee. What start *»fgJj«i^*52?a2SS! i^rm a Umr Hns thrwgh ths hsaoene t Where is Arcturus mentioned in the Scitp- ftneil _ 9 PICTURE OF THE HEAVENS. * JU^CJB. Where the new constellations nightly rise, And add a lustre to the northern skies." Garth's Ih-anslatum. Li70AM, In his PharaaUa^ says, "That Brutus, on the hnsy tiinns intent, Tu virtuous Cato's humble dwelling went 'Twas when the soleuin dead of night canie on, When bright CeUisto, toith her shining son, Now half that circle round the pole had run." This constellation is called Bootes^ says Cicero, (,Nai. Deo, Lib. ii. 42,) fTom • Greek word signifying a w^oner, or ploughman : and sometimes Areiophtfiax^ lirom two Greek words signifying near-keeper or bear-driver. "Arctophylax^ vulgo qui dicitur esse Bootes, Quod quasi temone adjunctum pre se quatit Arctmn." The stars in this region of the skies seem to have attracted the admiration of almost all the eminent writers of antiquity. Claudian observes, tliat "Bootes with his wain the north unfolds ; The southern gate Orion holds." And Aratua,* who flourished nearly 800 years before Claudian, mya, "Behind, and seeming to urge on the Bear, Arctophylaz, on earth Bootes named, Bheds oNsr the Arctic car his silver light." CENTAURUS. The Centaur. — This fabulous monster is represented by * This Is the poet whom St Paul refers to when he tells the Athenians, Acts zviL S8, that " some of their own poets have said," " Tov y*^ kxi ytvoc tT/uty : For we are also his offspring." These words are the beginning of the 5th line of the " Phenome- na," of Aratus ; a celebrated Greek poem written in the reign of Ptolemy Philadelphus. two thousand one hundred years ago, and afterwards translated into Latin verse bjr Cicero. Aratus was a poet of St. Paul's own country. The apostle borrows a^infrom the same poet, both In his Epistle to tiie Galaiians, and to Titus. The sulgeet of the goem was grand and interesting : hence we find it referred to m the writings of St. lemcnt, St. Jerome, St Chrysostom, CEcumenius, and others. As this poem describes the nature and motions of the stars, and the origin of the constellations, and is, more- over, one of the oldest compositions extant, upon this interesting subject, the author has taken some pains to procure a Polyglot copy/rom Qermany, together wltli the At- tronomicon of Manilius, and some other works of similar antiquity, that nothing shouhl be wanting on his part which could impart an interest to the study of the constella* tions, or illustrate the ftequent allusions to them which we meet with in the Scrip- tures. Dr. Doddridge says of the above quotation, that " these words are well known to be fbui»d In Atatus, a poet of Paail's own country, who lived almost 300 years before the apo3tle's time ; ana that the same woids, with the alteration of only one letter, are to be found in the Hymn of Cleanthee, to Jupiter, the Supreme Qod; which is, beyond comparison, the purest and finest piece of natural religion, of its length, which I know in the whole world of Pagan antiquity ; and which, so fhr as I can recollect, contains nothing unworthy of a Christian, or, I had almost said, of an inspired pen. The apos* tie mlgiit perhaps refer to Cleanthes, as well as to his countryman Aratus." Many of the elements and fiibles of heathen mythology are so blended with the in- spired writings, that they must needs be studied, more or less, in order to have a mora prouer understanding of numerous passages both in the Old and New l^stament. The great apostle of the Gentiles, in uttering his inspired sentiments, and in pen> ninf his epistles, often refers to, and sometimes quotes veibatim Arom the dlstinguishod writers who preceded htm. Thus, In 1 Cor. xv. 33, we have " Mj» ^rkAveta-B*' * ^Bu^ufftt tiBn Xf**^^* ojuiXi« KtK'it.* Be not deceived ; evil communications corrupt good manners ;" which is a literal quotation by the apostle fVorc the Thais of Menander, an inventor of Greek comedy, and a celebrated Athen^iin poet, who flourished nearly 400 years before the apostle wrote his epispe to the Corinthians. Thus Paul adopts the sentiment of tlie comedian, and it becomes hallowed by " the divinity that stirred within him." Ter- tulllan remarks, that " in rscioting this, the aposUe hath sancUfied the poet's senttmfitit ' How is the Centaur represented? MAP 1V.1 LCPUS. 00 tne figure of a man terminating in the body ol a horse^ hold- mg a wolf at arm's length in one hand, while he transfixes its uody with a spear in the other. Although this constellation occupies a large space in the southern hemisphere, yet it is so low down that the main part of it cannot be seen in our latitude. It is situated south of Spica Virginis, with a mean declination of 50°. It con- tains thiity-five stars, including two of the 1st magnitude, one of the 2d, and six of the 3d ; the brightest of which are not visible in the United States. TTtetOf is a star of between the 2d and 3d magnitude, in the east shoulder, and may be seen from this latitude during the month of June, being about 27° n. by E. from Spica Virginia, and 12° or 13° above the southern horizon. It is easily recognised, in a clear evening, from the circumstance that there is no other star of similar brightness, in the same region, for which it can be mistaken. It is so nearly on the same meridian with Arctunis tliat it culminates but ten miaulea before it. lota^ is a star of between the 4th and 5th magnitude, hi the west shoulder, 9^ W. of Thcta. It is about 26° almost directly south of Spica Vii^inis, and is on the meridian nearly at the same time. Mu and iVu, are stars of tne 4tn magnitude, in the breast, very near together, and form a regular triangle virith the two stars in the shoulders. A few degrees north of the two stars in the shoulders, are four small stars in the head. Tlie relative position of the stars in the head and shoulders is very similar to that of the stars iib the head and shoulders of Orion. HiSTomr. — Centaurs, in mytholiigy, were a kind of fabulous monsters, half men anfl half horses. Thi^ fable is, however, difTcrently interpreted; some suppose the Centaurs to have been a body of sheplierds and herdsmen, rich in cattle, who mliabited tlie mountains of Aacadia, and to whom is attributed the invention of pastoral jioctry. But Plutarch and Pliny are of opinion, that such monsters have really existed. Others say, that under the reign of ixion, king of Thessal;^, a herd of bulls ran mad, and ravaged the whole country, rendering the mountains Inaccessible ; and that some young men, who had found the ait of taming and mounting horses, undertook to expel these noxious animals, which they pur> sued on norseback, and thence obtained the appellation of Centaurs. Tills success rendering them insolent, they msulted the Lapiths, a people of Thesf aly ; and because, when attacked, they fled with great rapidity, it was sup< posed that they were half horses and half men ; men on horses being at that period a very uncommon sight, and the two appearing, especially at a distance, to constitute but one animal. So the Spanish cavalry at first seemed to the as- tonished Mexicans, who imagined the horse and his rider, like the Centaurs ot the ancients, to be some monstrous animal of a terrible form. The Centaurs, in reality, were a tribe of lApithse, who resided near Mount Pelion, and first invented the art of breaking horses^, as intimated by Vii]gU ■ — **The Lapithse to chariots add the state Of bits and bridles; taught the steed to bound; To turn the ring, and trace the maxy ground ; To stop, to flyj the rules of war to know; To obey the rider, and to dare the foe." LUPUS. The Wolf. — This constellation is situated next east oi •he Centaur, and south of Libra ; and is so low down in the What is the situation of this constellation ? What are the number and ma^iltrole of its stars? Describe the attuation ef Theta. H&m U it eatriiy recognised in a clear evety kng 7 IVTuu is its distance from the meridian cf Arcturus 1 Describe the star in tna west sfwuider. Describe the stars in the breasL Where Is the Wolf situated 1 100 nCTUUE or YUK HEAVENS. [jUNlL southern hemisphere, that only a few stars in the group are visible to us. It contains twenty-four stars, including three of the 3d mag nitude, and as many of the 4th ; the brightest of which, when on the meridian, may be seen in a clear evening, just above the southern horizon. Their particular situation, however, will be better traced out by reference to the map than by writ- ten directions. The most favourable time for observing this constellation, is towards the latter end of June. HiBTORT. — This constellation, according to foble, is Lycaon, Icinjg; of Arcadia, who lived about 3,600 years ago, and was changed into a wolf by Jupiter, because he offered human victims on the altars of ttie god Pan. Some attribute thts met- amori>lio8i8 to another cause. The sins of mankind, as thev relate, had become 80 enoniious, that Jupiter visited the earth to punish its wickedness and impiety. lie came to Arcadia^ where he was announced as a god, and the people oegaa to pay proper adoration to his divinity. Lycaon, how^ever, who used to sacrince all strangers to his wanton cruelty, laughed at the pious prayers of his subjects, and to try the divinity of the god, served up human flesh on his table. This im^ piety 80 offended Jupiter, that he immediately destroyed the house -of Lycaon, end changed him into a wolf. "Of these he murders one ; he boils the flesh, And lays the mangled morsels in a dish ; Some part he roasts ; then serves it u]^ so dress'd, And bids me welcome to his human feast Moved with disdain, the table I o'ertum'd, And with avenging llames the palace burn'd. The tyrant in a fright for shelter gains The neighb'ring fields, and scours along the plains : Uowling he fled, and fain he would nave spoke, But human voice his brutal tongue forsook. His mantle, now his hide, vrith rugged hairs. Cleaves to his back ; a famish'd face he bears ; His arms descend, his shoulders sink away To multiply his legs for chase of prey ; He grows a wolf." — Ovid, Met. B. i. LIBRA. The Balance. — This is the seventh sign, and eighth con- stellation, from the vernal equinox, and is situated in the Zo- diac, next east of Virgo. The sun enters this sigriy at the autumnal equinox, on the 23d of September ; but does not reach the constellation before the 27th of October. Virgo was the ffoddess of justice, and Libra, the scales, which she is usually represented as holding in her left hand, are the appropriate emblem of her office. When the sun en- ters the sign Libra, the days and nights are equal all over the How many stars does it contain? Under what circumstances may the brightest of them be seem How may the stars in this group be most conveniently traced outi When Is the most favourable time for observing this constellation ? How Is Libra sitr uated among the constellation =« of the Zodiac? At what sesison of the year does the son enter Libra? Who was Virgo, and what was the emblem of her office? What iM the relative lenj[th of the Oays and nights whcu the sun enters Llbrai MAP IV. J UBBA. 10. worJd, and seem to observe a kind of equilibrium, luce a balance. When, however, it is said that the vernal and autumna equinoxes are in Aries, and Libra, and the tropics in Cance* and Capricorn, it must be remembered that the signs Ariet and Libra, Cancer and Capricorn, and not the constellationi^ of these names are meant ; for the equinoxes are now in th%i constellations Pisces and Virgo, and the tropics in Gemim and Sagittarius ; each constellation having gone forward one sign in the ecliptic. About 22 centuries ago, the constellation Libra coincided with the sign Libra ; but having advanced 30° or more in the ecliptic, it is now in the sign Scorpio, and the constellation Scorpio is in the sign Sagittarius, and so on. While Aries is now advanced a whole sign above the equi- noctial point into north declination, Libra has descended as far below it into south declination. Libra contains fifty-one stars, including two of the 2d mag- nitude, two of the 3d, and twelve of the 4th. Its mean decli- nation is 8° south, and its mean right ascension 226°. Its centre is therefore on the meridian about the 22d of June. It may be known by means of its four principal stars, form- ing a quadrilateral figure, lying northeast and southwest, and having its upper and lower comers nearly in a line running north and south. The two stars which form the N. E. side of the square, are situated about 7° apart, and distinguish the Northern Scale. The two stars which form the S. W. side of the square, are situated about 6° apart, and distinguish the Southern Scale. Zubeneschitmali, in tlie Southern Scale, about 21^ E. of Spica, and 8^ E. of Lambda Virginia, is a star of the 2d magnitude, and is situated very n^ar the ecliptic, about 42j^^ E. of the autumnal equinox. The distance from this star down to Theta Centauri, is about 23^, with which, and Spica Virginis, it forms a large triangle, on the right. Zubenelgemabi, the uppermost star in the Northern Scale, is also of the 2d magnitude, 9j^^ above Zubeneschamali, towards the nortlieast, and it comes to the meridian about twenty-six minutes ailer it, on the 23d of June. Zubenelge* mabi is the northernmost of the four bright stars in this figure, and is exactly oimosite the lower one, which is 11*^ south of it. ZubenPiakrabij is a star of the 3d magnitude in the Northern Scale, 7° S. E. of Zobenelgemabi, and nearly opposite to Zubeneschamali, at the distance of 11° on the east. These two make the diagonal of the square east and west. Iota, is a star of the 3d magnitude, and constitutes the southernmost comer of When it Is said that the vernal and autumnal equinoxes are in Aries and Libra, and the tropics In Cancer and Capricorn, what is meant? In what constellations, then, are the equinoxes and the tropics situated? When did the constellation of Libra coincide with the aisrn of that name? In what sign Is the constellation Libra now situated; What are the number and magnitude of the stars in Libra *> What are its right ascen- sion and declination 7 Whenl.s its centre on the meridian? How may this constella don be known? What figure do the three upper stars In this tagure form? What stars distlngaish the Northern Scale? What the Southern? DneribeZtibenetchamaH, WUh whai other 9tan doea U farm a large trianglel De»cribe thepr^^if^valjtar in the Korthem Scale. DeeerOeihepeeMonqf ZubenhakraH. DeecriU^hepotUionqriota, 9* 100 t*lCTCRE OK TUf UKAVEN^ [jt/NB* the square. It is about 6<> 8. B. of Zubeneschamali, and ll^^ S. of Zubeue^e roabL with which it forms the other diagonal north and sooth. Zeoett^Jgubij is a star of the 3d magnitude, situated below the Southern ScalOi at the distance of 6° from lota, and marks the southern Umit of tlie Zodiac. It is situated in a right line with, and nearly midway l>etween, Spica Viixinis and Beta. Bcorpionis ; and comes to the meridian nearly at the same moment with Nekkari in the bead of Bootes. The remaining stars in this constellation are too small to engage attention. The scholar, in tracing out this constellation in the heavens, will perceive that Lambda and Mu, which lie in the feet of Virgo on the west, form, with Zi^nes- chamali and Zut)cnelgemabi, almost as handsome and perfect a figure, as the other two stars in the Balance do on the east HisTORY.^The Libra of the Zodiac, sa^s Maurice, m his Indian Antiqnkiea, is perpetually seen upon all the hieroglyphics of E^pt; which is at once an argU' ment of the ereat antiquity of this asterism^ and or the probability of its having been originaliy fobricated by the astronomical sons of Misraim. In some few zodiacs, Astrsea, or the virgin who holds the ImlaBce in her hand as an emblem of equal justice^ is not drawn. Such are the zodiacs of Eetne and Dendex^ Ilumooldt is of opinion, that although the Romans introduced this constellation into their zodiac in the reign of Julius Cesar, still it might have been used by the Egyptians and other nations of very remote antiquity It is generally supposed that the figure of the balance has been used by all nations to denote the equality of the days and nights, at the period of the sim's arriving at this sign. It has also been observed^ that at this season tliere is a greater uuiformity in the temperature of the air all over the earth's surface. Others affirm, that the beam only of the balance was at first placed among the btars, and that the Egyptians thus honoured it as their Nilcmcter, or instrument by which they measured the inundations of the Nile. To this custom of measur* ing the waters of the Nile, it is thought the prophet alludes, when he describes the Almighty as meaawring the teatersin ike houoto of his hand. — ^Isa. Jd. 12. The ancient husbandmen, according to Virgil, were wont to regard this sign as indicating the proper time for sowing their winter grain : — "But when Astrasa's balance, hung on high, Betwixt the nights and days divides the sky, Then yoke your oiten, sow your winter grain. Till cold December comes with driving rain." The Greeks declare that the balance was placed among the stars to perpetuate the memory of Mochus, the inventor of weights and measures. Those who refer the constellations of the Zodiac to the twelve tribes of Israeli ascribe the Balance to Asher. \ SERPENS. The Serpent. — There are no less than four kinds of ser pents placed among the constellations. The first is the Hydra, which is situated south of the Zodiac^ below Cancer, Leo and Virgo ; the second is Hydras, which is situated near the south poie ; the third is Draco, which is situated about the north pole ; and the fourth is the Serpent, called Serpens Ophiuchi, and is situated chiefly between Libra and Corona Borealis. A large part of this constellation, however, is so blended with Ophiuchus, the Serpent-Bearer, who grasps it in both hands, tnat the concluding description of it will be deferred until we come to that constellation. "The Serpens Ophiuchi winds his spire Immense ; fewer by ten his figure trace ; What 9tar in this ccnsteUatUm marks the wuikem Umit qfthe Zodiac? Bow namy ui'idsofserpentsliavabeen placed among the constellations} Mention then andthMT •lnuitlons. With what U a laige part of Mi conatellatlon UendeA* MAJ> V.^ SEfUXNS. 103 On6 of the aecoud nnk ; ten shun the right \ And seven, he who benn the moneter hioee.** Those stars which lie scattered along for about 25^, in a serpentine direction between Libra and the Crown, mark tho body and head of the Serpent. About 10^ directly S. of the Crown there are three stars of the 3d magnitude, which, with sereral smaller ones, distin- guish the head. Unitk, of the 2d magnitude, is the pnncipal star in this con- stellation. It is situated in the heart, about 10^ below those in the head, and may be known by its being in a hne with, and between, two stars of the 3d magnitude^-the lower one, marked Epsihm, being 2i<^, and the umper one^ maiked IMUu about 5^o froni it. The direction of this Ime is N. N. W. ana S. 8. E. Unuk may otherwise be known by means of a small star, just above it, nfiarked Lambda. In that part of the Serpent which lies between Corona Bo- realis and the Scales, about a dozen stars may be counted, of which five or six are conspicuous. For. the remainder of this constellation, the student is refer* red to Serpentarius. "Vast as the starry Serpent, that on hifh Tracks tlie clear ether, and divides the akj. And southward winding from the Northern Wain. Shoots to remoter spheres its glittexing trahL" — Statius. History. — ^tlie Hivites, of the Old Testament, were worshippers of the Ser- pent, and were called OpMtes. The idolatry of these Ophites was extremely ancient, and was connected with Tsabaimm, or the worship of the host of heaven. The iMresy of tiie Ophites, mentioned by Moshehn to his Ecclesiastical History, originated, perhaps, m the admission into the Christisn church of some remnant of the w^cient and popular sect of TsabiUsts, who adored the celestial Serpent According to ancient tradition, Ophiuchus is the celebrated phYBician iEseu> laiios, son of Apollo, who was instructed in the healii^ art by Chiron the Cen- taur ; and the serpent, which is here placed in his hands, is understood by some to be an emblem of his sagacity and prudence ; wfaHe others sunpose it was designed to denote his skill in healinc the bite of this reptile. Biblical critics imachie that this constellation is alluffed to in the foUowtaig passage of the book of ^b : — "By his spirit He haih garnished the heavens: hjs hand hath formed the crooked serpent.'* Mr. Green supposes, however, uiat the inq>ired writer here refers to Draco, because it is a more ob^ous constellation, being nearer the pole where the constellations were more aniversally noticed ; and moreover, because it is a more ancient constellation than the Serpent, and the hieroglyphic by which the EgypUana nsoally represented the heavens. CORONA BOREALIS. The Northebm Crown. — This beautiful constellation suiy be easily known by means of its six principal stars, which are so placed as to form a circular figure, very much resem- Whaft stars mazk the bead and iMdy of the Swpenn I>S:«2«-%S2i2S8 »fr thlsconsteUatlon. How may it he known? ^^^V^n'S^SSihnlLtetSmCom MUiy stars maybe counted in that part of tbe^eonsteUstlMkjjrtirailJes between cv.v.- Somalia aiylttieecalesi How iwjOwonaBoieiais be easily knowni *04 PICTURE or THC HEAVENS. | JURi. bling a wreath or crown. It is situated directly north of the Serpent's head, between Bootes on the west and Hercules on tlie east This asterism was known to tbe Hebrews bv tb« name of Atarothf and bjthis name the stars in (Corona Boreatis are called, In the East, to this day. Alph-accOy of the 3d magnitude, is the brightest and middle star m the diadem, and about 11^ E. of Mirac, in Bootes. It b Yery readily distinguished from the others both on account of its i)osition and superior brilliancy. Alphacca, ArcturosL and Se^inus. form nearly an isosceles triangle, the vertex oi which IS at Arcturus. This constellation contains twenty-one stars, of which only six or eight are conspicuous ; ana most of these are not larger than tbe 8d magnitude. Its mean declination is St^ north, and its mean right ascension 23§® ; its centre is therefore on the meridian about the last of June, and the fost ctf* July. ** And, near to HeUcCy effhlgeBt rays Beam, Ariadne^ from thy starry crown : Taentif and one her stars ; but eight alone Conspicuous ; one doubtful, or to claim The second order, or accept the third." HiRORT.— This beautiful little cluster of stars is said to be in commemoration of a crown presented b^ Bacchus to Ariadne, the daughter uf Minos, second kins of Crete. Theseus, tcmg of Athens, (1235 B. C,) weus shut up in the celebrated labyrinth of Crete, to be devoured by the ferocious Minotaur which was con- fined in that place, and which usually fed upon the chosen young men and middens exacted from the Athenians as a yearly tribute to the tyranny of Minos , but Theseus slew Xhe monster, and being furnished with a clue of thread by Ariadne, who was passionately enamoured of him, he extricated himself from the difficult windings of his confinement. He afterwards married the beautiful Ariadne, according to promise, and car- ried her away ; but when he arrived at the island of Naxos, he deserted her, notwithstanding he had received from her the most honourable evidence of ai* tachment and endearing tenderness. Ariadne vras so disconsolate upon being abandoned by Theseus, that, as some say, she hanged herself; but' Piutarcn says that she lived many years after, and was espoused to Bacchus, who loved ner with much tenderness, and gave her a crown of seven stars, wliich, after her death, wu placed among the stars. *< Resolves, for this the dear engaging dame Should shine forever in the rolls ofiame ; And bids her crown among the stars be placed* And with an eternal constellation grac'd. The golden circlet moimts ; and, as it flies, Its diamonds twinlcle in the distant skies ; There, in their pristine form, the gemmy rays Between Alcides and the Dragon blaze." Manifiua^ in the first book of his Aatronomie&n, thus speaks of the Crown. ** Near to Bootes the bright crown is view'd And shines with stars of different magnitude : "Where Is It situated? Describe the principal star In the group. What geometrical 5S2!? ^Ip^J"**!* by the stars in this neighbourhood i What are &e number and nuS^ 2S!S«^*^^»r?'?/.£^V?.^i.W.^^^^ What are its mean decunauon and riSffS. censtonf When is It on car meridian} V<. i UKSA MINOIU MI6 Or placed in froat aoove the rest displays A yigorons li^ht, and darts nirpriainff rays. This shone, since Theseus first his fiith betny'd Tlie luonumcnt of the forsaken makL" URSA MINOR. The LirrLE Bear. — This constellation, though not re- markable in its appearance, and containing but few conspl- cuoas stars, is, nevertheless, justly distinguished from all others for the peculiar advantases which its position in the aeavens is well known to afford to nautical astronomy, and especially to navigation and surveying. The stars in this group being situated near the celestial pole, appear to revolve about it. very slowly, and in circles so smalt as never to descend below the horizon. In all ages of the world, this constellation has been more nniversally observed, and more carefully noticed than any other, on account of the importance which mankind early at* tached to the position of its principal star. This star which is so near the true pole of the heavens, has, from time immemorial, been denominated the North Polar Star. By the Greeks it is called Cynosyre ; by the Romans, Cynosura^ and by other nations, Alruccahah. It is of the 3d magnitude, or between the 2d and 3d, and situated a little more than a degree and a half from die true pole of the heavens, on that side of it which is towards Cassi- opeia, and opposite to Ursa Major. Its position is pointed out by the direction of the. two Pointers, Merak and Dubhe, whicn lie in the square of Ursa Major. A line joining Beta Cassiopeiae, which lies at the distance of 32^ on one side, and Megrez, which lies at the same distance on the other, will pass through the polar star. So general is the popular notion, that the North Polar Star is the true pole of the world, that even surveyors and navigators, who have acquired considerable dexterity in the use of the compass and the quadrant, are not aware that it ever had any deviation, and consequently never make allow- ance for any. All calculations derived from the observed posi- tion of this star, which are founded upon the idea that its bearing is always due north of any place, are necessarily er- roneous, since it is in this position only twice in twenty-four hours ; once when above, and once when below the pole. What renders Ursa Minor an hnportant oonstellatimil What is lu situation with respect to the North Pole, and how do its stars appear to revolve around this poisf Why has this coustellation been mote universally observed, in all ages of the wortd, than any othei ? What is this star denominated i What are Its magnitade and posl* Uon? How is its posiUon pointed out? How is it siUated with resprot tojjtegjw sni Beta Casslopei?B? is it generally considered to be the north pole of ti»e neavensi Are calculations founded upon this notion correct] t06 ' PICTURE OP THF Hr.AVE.N8. ljlJ?f«' According to the Nautical Almanac, the mean distance o/ this star from the true pole of the heavens, for the year 1833 is 1° 34' 53", and its mean right ascension is 1 hour and 19 seconds. Consequently, when the right ascension of the me- ridian of any place is 1 nocr and 19 seconds, the star will be exactly on the meridian at that time and place, but 1° 34' 63" (wove the true pole. Six hours after, when the right as- cension of the meridian is 7 hours and 19 seconds, the star will be at its greatest elongation, or 1^ 34' 53" directly west of the true pole^ and parallel to it, with respect to the horizon ; and when tne right ascension of the meridian is 13 hours and. 19 seconds, the star will be again on the meridian, but at the distance of 1® 34' 53" directly below the pole. In like manner, when the right ascension of the meridan is 19 hours and 19 seconds, the star will be at its greatest east- ern elongation, or 1° 34' 53" east of the true pole ; and when it has finished its revolution, and the right ascension of the meridian is 25 hours and 19 seconds, or, what is the same thin^, 1 hour and 19 seconds, the star will now be on the meridian again, 1° 34' 53" above the pole. N. B. The right ascension of the meridian or of the mkl-heaTen, is the dis- tance of the first point of Aries from the meridian, at the tune and place of ob- tervation. The right ascension of the meridian for any time, is founi I, by adding to the given time the sun's right ascension at the same time, and deducting 1» hours, when the sum exceeds 24 hours. From the foregoing facts we learn, that from the time the star is on the meridian, above the pole, it deviates farther and farther from the true meridian, every hour, as it moves to the west, for the space of six hours, when it arrives at its greatest elongation tvest, whence it reapproaches the same meridian below the pole, during the next six hours, and is then again on the meridian ; being thus alternately half the time west of the meridian, and half the time east of it. Hence, it is evident that the surveyor who regulates his compass by the North Polar Star, must take his observation when the star is on the meridian, either above or below the pole, or make allowance for its altered position in every other situation. For the same reason must the navigator, who ap- plies his quadrant to this star for the purpose of detemiining the latitude he is in, make a similar allowance, according as its altitude is greater or less than the true pole of the hea- What is the present distance of this star ftom the true pole of the heavens? What Is tts mean right ascension? When is it on the meridian, and what then Is its bearing tnm the pole. What is its situation six hours afterwards? What is its situation six hours after that? What is its situation when in its thlnl quadrant ? ninu do you «n- dentanA by the right ascension ttf the meridian^ or qf the mid-heaven 7 Hono do you find the risrht ascension of the mid-heaven 7 In what manner does the north star de> vlatfi from the meridian during one revolution ? How do these &cts concern the sur- veyor' IIAF VI.J ORSA MINOK. 107 reas ; for we hare seen that it is alternately half the time above and half the time below the pole. I'he method of finding the latitude of a place from the alti- ^ tude of the polar star, as it is yery simple, is very often re- sorted to. Indeed, in northern latitudes, the situation of this star is more favourable for this purpose tnan that of any other of the heavenly bodies, because a single observation, taken at any hour of the night, with a good instrument, will give the true latitude, without any calculation or correction, except that of its polar aberration. If the polar star always occupied that point in the heavens which is directly opposite the north pole of the earth, it would be ea^y to understand how I^tude coald be determined from it in the northern hemisphere ; for in this case, to a person on the equator, the poles of the world would be seen in the horizon. Consequently, the star would appear just visible in the northern horizon, with out any elevation. Should the person now travel one degree towards the nortii, he would see one degree below the star, and he would think it had risen one degree. And since we alwajrs see the whole of the upper hemisphere at one view, when there is nothing in the horizon to obstruct our vision, it follows that if we should travel 10° north of the equator, we should see just 10^ below the pola» which would then appear to have risen 10*^ ; and should we stop at the 42a de- gree of north latitude we should, in like manner, have our horizon just 42^ below the pole, or the pole would appear to have an elevation of 42°. Whence we de> rive this (general truth : The elevation of the pole of the equator, ia altoaya eqwU to the latitude of the place of observation. Any instrument, then, wtiich will give us the altitude of the north pole, will give us also tiie latitude of the ^lace. The method of illustrating this phenomenon, as given in most treatises on the globe, and as adopted by teachers generally, is to tell the scholar that the north pole rises higher and nigher, as he travels fariher and farther towards it In other words, whatever number of degrees he advances towarcb tiie north pole, so many degrees will it rise above his horizon. Thia is not only an obvious erraur in principle, but it misleacls the apprehension of the pupil. It is not that the pels » elevated^ but that our horizon is depressed as we advance towards the north. The same dbjection lies aj^inst the artificial globe ; for it ought to be so fixed that the horizon might be raised or depressed, and the pole remain in its own invariable position. Ursa Minor contains twenty-four stars, including three of the 3d magnitude and four of the 4th. The seven principal stars are so situated as to form a figure very much resemblinff that in the Great Bear, only that the Dipper is reversed, ana about one half as large as the one in that constellation. The first star in the handle, called Cynosura, or Alrtccca" bahy is the polar star, around which the rest constantly re- volve. The two last in the bowl of the Dipper, corresponding to the Pointers in the Great Bear, are of the 3d magnitade, V7hy is the method of finding the latitude by the polar star, often resorted to7 Why Is the poslilon of this star fovoursdile to tMs purpose? If the north star perfectly co- incided with the north pole qf the heavens, where wouUL it be seen from the eftuatort Should a person travel one degree north cfthe equator, where would the star appear thml Suppose he should travel 10 deffreen north cf the equator 7 Suppose he wore to stop atthcistd degree of north latitude 7 MTluU general truth results from these facta ? What, then, U aU we want, tojlnd the latitude of any place ? Of what advantage torn tnariner, is an instrument which wUl give the altitude of the pole 7 What are the number and magnitude of the stars, contained In Ursa Minor? What Ugandow seven principal stars form? Describe the first ia the handle of the Little Inpper. De •cvfbe we two last in the bowt of the Dipper JOS PICTURE OP THE MEATElfS, |Ji;?rB« and situated about 15° from the pole. The bn^btest of them is called Kochab, Which signifies an axle or hinge, probably in reference to its moring so near the axis of the earth. Kochab may be easily known by its being the brightest and middle one of three conspicuous stars forming a row, one of which is about 2°, and the other 3°, from Kochab. The two brightest of these are situated in the breast and shoulder of the animal, about 3° apart, and are called the Guards or Pointers of Ursa Minor, They are on the meridian about the 20th of June, but may be seen at all hours of the night, when the sky is clear. Of the four stars which form the bowl of the Dipper, one is so small as hardly to be seen. They lie in a direction to- wards Gramma in Cepheus; but as they are continuctial pointa; and which were much noticed by the astronomers of t)ie East. About 84^ northwest of Antares, is a star of the 2d mag- nitude, in the head of the Scorpion, called Grqffias. It is but one degree north of the earth's orbit. It may be recognised by means of a small star, situated about a decree northeast of it, and also by its forming a slight curve with two other $tars of the 3d magnitude, situated below it, each about 3° apart. The broad part of the constellation near Grafiias, is powdered with numerous small stars, converging down to a point at Antares, and resembling in figure a boy's kite. As you proceed from Antares, there are ten conspicuous stars, chiefly of the 3d magnitude, which mark the tail of the kite, extending down, first in a south, southeasterly direction, about 17°, thence easterly about 8° further, when they turn, and advance about 8° towards the north, forming a curve like a shepherd's crOok, or the bottom part of the letter S. This crooked line of stars, forming the tail of the Scorpion, is very conspicuous, and may be easily traced. The first star below Antares, which is the last in the baclc, is of only the 4th magnitude. It is about 29 southeast of Antares, and is denoted by tlie Gr^elc same of T. Epnlon^ of the 3d magnitude, is the second star from Antares, and the first in the taiL It is situated about 7° below the star T, but inclining a little to the ea:jt. Afti, of the 3d magnitude, is the third star from Antares. It is situated 4^<^ be- low Epsilon. It may otherwise be known by means of a siuall star close by it. oa the left ZetOy of about the same magnitude, and sltuatefl- about as far below Mu, is tho fourth star from Antares. Here the line turns suddenly to the east. Eta, also of the 3d magnitude, is the fifth star from Antares, and about 3^'^ eastofZeta. Theta, of the same magnitude, is the sixth star from Antares, and about Ajt^ east of Eta. Here, the line turns again, curving to the north, and terminates m a couple of stars. Iota, is the seventh star from Antares, S^^ above Theta, curving a little to the left. It is a star of the 3d magnitude, and may be known by means of a small star, almost touching it, on the east Kappa, a star of equal brightness, Is less than 2° above Iota, and a liule to the ijgiiu Howls Antares otherwise distinguished? Wliat is its declination? What Is ths S"® 5t**lP*5?*"*? ^^ meridian J What nautical importance is attached to Its position 1 Describe Grafflas 7 How may it be recognised? What is the appearance of the constel- wion between Grafflas and Antares? How many conspicuous stars below Antares f 23** "I? *5?.V n»gnltttde and general direction? De$cnbe the first star below An- 5KS. fiK?* 'H.**??S' ftarhelow Antares. Describe the third star, and teU hm» toyp5t!rS?g I>«**raeVufyurth. Deecribethejifih. tDescribe Theta. Detaiba •SAP v-l SCORPia ill Lemthj of the 3d magnitude, is the brightest of the two last In Ihe ta!^ and la •ituated about 3^ above Ki^pa, still further to the right It may readily Ho known by nmtkns of a smaller star, close by it, on the west. This IS a very beautiful group of stars, and easily traced cut in the heavens. It furnishes striking evidence ot the fa- cility with which most of the constellations may be so accu- rately delineated, as to preclude every thing like uncertainty in the knowledge of their relative situation. "The heart with lustre of amazing force, Refulgent vibrates ; fuiut the other parts, And ill-defined by stars of meaner note." Hjstoky.— This sign was anciently represented by various symbols, sometimes by a snake, and sometimes by a crocodile ; but most commonly by the scorpion. This last symbol is foimd on the Mithraic monuments, which is pretty good evi- dence thai these monuments were constructed when the vernal equinox accord* ed with Taurus. On both the zodiacs of D«idera, there are rude delineations of this animal ; that on the portico differs considerably from that on the other zodiac, now in the Louvre. Scorpio was considered by the ancient astrologers as a sign accursed. Th« Egyptians ficed the entrance of the sun into Scorpio as the commencement of the reign of Typhon, when the Greelis fabled tlie death of Orion. When the sun was in Scorpio, in the month of Athyr, as Plutarch informs us, the Egyptians enclosed the body of tlieir god Ojiiris in an ark, or chest, and during this cere- mony a great annual festival was celebrated. Three days after the priesCi had enclosed Osiris in the ark, they pretended to have found him again. The deaih of Osiris, then, was lamented when the stm in Scorpio descended to the lower hemisphere, and when he arose at the vernal equino^ then Osiris was said to be born anew. The Egyptians or Chaldeans, who first arranged the Zodiac, might have placed Scorpio in this part of tlie heavens to denote that when the sun enters, this si|;n, the aiseases incident to tlie fruit season would prevail ; since Autumn, which abounded in fruit oflen brought with it a great variety of diseases, and might be thus fitly represented by that venomous animal, the scorpion, who, as he re- cedes, wounds with a sting in his tail. Mars was the tutelary deity of the scorpion, and to this clrcunstance is owing •II that jargon of the astrologers, who say that there is a great analogy between the maUgn influence of the planet Mars, and this sign. To this also is owing the doctrine of the alchymists, that iron, which metal they call Mars, is under the dominion of Scorpio ; svthat the transmutation of it into gold can be effected only when the sun is in this sign. . . > vi 'nie constellation of the Scorpion is very ancient Ovid thus mentions it m nia oeaatiftil fable of Phaeton : — " There is a place above, where Scorpio bent, In tail and arms surrounds a vast extent ; In a wide circuit of the heavens he shines, And fills the place of two celestial signs." AccordlnK to Ovid, this is the famous scorpion which sprang out of the earth •t the command of Juno, and stun^r Orion ; of which wound he died. It was in this way the imperious goddess chose to punish the vanity of the hero and the hunter, for boasting that there was not on earth any animal which he could not conquer. "Words that provok'd the gods once from him fell, *No beasts so fierce,' said he, 'but I can quell ;' When lo ! the earth a baleful scorpion sent, To kill Latona was the dire intent ; Orion saved her, tho' himself was slain, But did for that a spacious place obtain In heaven : 'to thee my life,* said she, *W€udeart And for thy merit shine iUuatrioua there.* " IH9tnb€ Lentth. liH nCTUBE OF TBE BEAVENS. {jQV*Y« MSatkongh both Orion and Seorpio wer« honoured bj th»6elefltial« «im « 8 lace among the stars, yet their attuations were so ordered that when one rose lie other should set, and vice versa ; so that they never ^>pear in the same hemisphere at the same time. In tne Hebrew zodiac this sign is allotted to Dan. because it is written, ''Dan fldiall be a serpent by the way, an adder in the path." HERCULES. Hercules is represented on the map invested with the skin of the Nemsan Lion, holding a massy club in his right hand, and the three-headed dog Cerberus in his left. He occupies a large space in the northern hemisphere, with one foot resting on the head of Draco, on the nortn, and his head nearly touching that of Ophiuchus, on the south. This constellation extends from 12° to 50" north declination, and its mean right ascension is 255° ; consequently its centre is on the meridian about tlie 21st of Julv. It is bounded by Draco on the north, Lyra on the east, Ophiuchus or the Serpent-Bearer on the south, and the Ser- pent and the Crown on the west. It contains one hundred and thirteen stars, including one of the 2dj or of between the 2d and 3d magnitudes, nine of the 3d magnitude, and nineteen of the 4th. The principal star is Has Algethi, is situated in the head, about 25° southeasi of Corona Borealis. It may be readily known by means ol another bright star of equal magnitude, 5° east, southeast oi it called Ras Alhague. Ras Alha^e marks the head of Ophiuchus, and Ras Algethi that of Hercules. These two stars are always seen together, like the bright pairs in Aries, Gemini, the Little Dog, &c. They come to our meridian about the 28th of July, near where the sun does, the last of April, or the middle of August. About midway between Ras Algcthi on the southeast, and Ariadne's Cro\ita on the northwest, may be seen Beta and Gainma, two stars of the 3d magnitude, situated in the west shoulder, about 3° apart The northernmost of these two is called Rutilicua. Those four stars in the shapA of a diamond, &^ or 10^ southwest of the two in the shoulder of Hercules, are Situated in the head of the serpent About 120 E. N. E. of Rutilicus, and 10^^ directly north of Ras Algethi, are two stars of the 4th magnitude, in the east shoulder. They may be lenown by two very minute stars a little above them on the left. The two stars in each fthoukier of Heicules, with Ras Algethi in the head, form a regular triangle. The left, or east arm of Hercules, which grasps the triple-headed monster Cerberus, may be tr aced by means of three or four stars of the 4th magnitude. How is the constellation Hercules represented? What space does It occupy, and what is Its situation in the heavens? What are its declinatlun and right ascension? when is Its centre on the meridian? How Is it bounded? What are the ntunber and mngnitude of Its stars? Describe the principal star. What do Ras Algethi and Ras Alhague serve to mark? When are they on our meridian? Describe the eitua- tion qfBsta andOamma. What ia the northemmoet qf these two caUed 1 What four etmra are eUuaxea 8© or iqo s. If. qfthe two in the ehoutder 7 Describe the stars 7a, in the nonhwest comer, may be known bj its being in a row with two smaller stars, extending towards the northwest and about 4^ apart The stars of the 4th magnitude, just south of the Itoagon's nead point out *h.'* left foot and ankle of Hercules. tSeveral other stars, of the 3d and 4th magnitudes^ may be traced out in this constellatton, by rclerence to the map. History. — ^This constellation is intended to immortalize the name of Hercules the Theban, so celebnUed in antiquity for his heroic valour, and inYiudbls prowess. According to the ancients, there were many persons of this name. Of all these, the son of Jupiter and Alcmena is the most celebrated, and to him the actions of the others have been generally attributed. The birth of Hercules was attended with many miraculous events. He wm brought up at TiryntAus, or at lliebes, and before he had completed his eighth mouth, the jealousy of Juno, who was intent upon his destruction, sent two snakes to devour him. Not terrified at the sight of the serpents, he i>oldly seized them, and squeezed them to death, while his brother Iphicles alarmed the house with nis frightful shrieks. He was early instructed in the liberal arts, and iioon became the pupil of the centaur Chiron, under whom he rendered himself the most valiant and aceont- plishcd of all the heroes of antiquity. In the l^h year of his age, he com- mf'nced his arduous and glorious pursuits. He subdued a lion that devourea the flocks of his supposed father, Auiphitrvon. After he had destroyed the Uon, ho delivered his country from the annual tribute of a hundred oxen, which it paid to Erginus. As Hercules, by the will of Jupiter, was subjected to the power of Eurystheosr end obliged to obey him in every respect, Eurystlieus, jealous of his rismg fiune and power, ordered him to appear at Mycense, and perform the labours which, by priority of birth; he was empowered to impose upon him. Hercules refused, but afterwards consulted the oracle of Apollo, and was told that he must be sub> servient, for twelve years, to the will of Eurystheu^ in compliance with tbs commands of Jupiter ; and that after he had achieved the most celebrated la^ hours, he should be reckoned in the number of the gods. So plain an answer determined him to go to Mycenae, and to bear with fortitude whatever soda or * men should impose u^ion him. Eurystheus, seeing so great a man totaUv sub* iected to him, and apprehensive of so powerful an enemy, commanded him to achieve a number of enterprises the most difficult and arduous ever known, generally called the Twblvb Labours of Hebculbb. Deing furnished with complete armour by the favour of the gods, he boldly encountered the imposed labours. 1. He subdued the Nemeean Lion in his den, and invested himself with his skin. 2. He destroyed the Lernsean Hydra, with a hundred hissinc heads, and dip ped his arrows in the gall of the monster to render their wounds incurable. 3. He took alive the stag with golden horns and brazen feet, so famous for its incredible swiftness, after pursuing it for twelve months, and presented it, un- hurt, tp Eurystheus. 4. He took alive the Erimanthian Boar, and killed the Centaurs who opposed him. 6. He cleansed the sUblesof Augias, in which 3000 oxen had been confined for many years. 6. He kuled the camiverous birds which ravaged the country of Arcadia, and f«d on human flesh. , ^ ^ ^ . . 7. He took alive, and brought into Peloponnesus, the wild bull of Crete, which no mortal durst look upon. ___^__^_«-. w.___-.— .— . " How U the head qfCerherw diatintruithedj Therearefmnjtm^n^^^ imgntar wuare, in the body ^ Hereuie9--de9crtbejfu»iu rin^^ ST^i FtrDmcrhe the Htwttion qfEta. What ttan point w^r <** *^« Jw * w *-v.- 10* ihe queen Qfitae AmuDDi, a, ibruildcblE aMun of erron, Ung of Gulei, mai brougtil tMtj bU na [ppLea from Ihe gBrdcn nf Ihe Ho^perWea, whid IP to Ihe eaith Ihe Ihree-hendeddosCerberm, Iht ttve 1ahoi]THDf Hf^rcTileian onlf > fipintlre np- » of Ihe tbn through the twelve eleiifi of Ih« »<> "Tbalsy recordiUM libouri, and Ihe pnier, And all the Imuianil uu of HeicDlei. Tim, how Uu mifhiv babe. Khtii nnih'd la Tha lerixiiti MnDfliBd nitb bb Infuil biodi ; TtieiiiU b jttn ud ouUchleaB force ba ire The l£elBliui will* lad Trojan oveithisw ; BaiJdee m IhouHod hoxardi tbej relate^ Pmcnred by Jimo^i and EuriilheuB' hale- Thy bandK imeociqafli'd hero, coaLd subdue Hie dood-Doin Ooitiun, and the nHnster ci Nor thj leiMleu arm the bull wlltittooil ) NDrbe,tliBRiaiincteiTDiirorihe wood. The Eriple porter of the BijrfUn Kal With lolUiu tonfoe lay fawnlnf u Otj feet, And, flEiiecT wUhfear, forf ot ihe muixled meJ The Infernal waters [remUed at Ihr sight : Thee, god, no Ace of danger coald aflnihl ; Nor huge Typbcua, nor the unnuinber'd ana Incrsaaed wiUi hiiaing headi, in Letna'a laVe deUvered himself up to the king of Myc — ■ - — ' "■- ' Colehli. HeaasleteJlheiodBlnlheirwi him alone thai Jupiter obtained Ihe cici la«ed TiDj. the broiher of his beioved iole ; in Ihe thirdhe ntleujpledlo canr awar the sa- cred Eiipod from ApoUo'B lemple ai Delphi, for which Ihe oracle toLd him he TDUBt be aold aa a bIbvc, He waa Bold accordingly Id Omphole, queen of l'?<^ KoneBua^ eTid re-eEiabllBhed on the dirone of Sparta his friend IVndarua, who d been eipelled by Uinnocoon. He becaoie enamoured of Dejanira, whoD^ alter havlnf OTef come all his itrals, he married ; but n« obliged to leave bia blher-ln-lan'a kingdom, becanae heliad InadTerteiillT hilled a man wMb a blow ofhlaBst. HerellredtothecounorCey^kbigofTrachlna,indinhlswa7Wu •tapped br the streams of the Erenua, iihere he alew the Centanr Neasna,
to the eastward of the place we are now in, be then eeen exaethr n >nh nf us still, without changing its position so much as the thickness of a sfM- der's web. These observations were subsequently repeated, with but little intenniSsion, for twenty years, by the most acute observers in Europe, and with telescopes varying from 12 feet to 36 feet in length. In the meantime, Dr. Bradley had the bonour of announcing to the world the very nice discovery, that the motion of tight, combined toith the progressive motion of the earth in its orbit, causes tns heavenly bodies to be seen in a different position from tohat they toould be, if the eye were at rest. Tims was established tlie principle of the Aberration qf Light. This principle, or law, now Uutt it is ascertained, seems not only very plain, but seir-evident. For if light be progressive, the position of the telescope, in ordei to receive the ray, must be dinerent from what it would have been, if light had been instantaneous, or if the earth stood stilL Hence the place to which the tel- escope is directed, will be different from tbe true place of the object. Tlie quantity of this aberration is determined by a simple proposition. The earth describes 59' 8" of her orbit m a day —3648"', and a ray of light comes fro«n the sun to us in 8' 13"- 493" : now 24 hours or 86400" : 493" : : 3&18" : 22" ; which is the change in the star's place, arising from the cause abovemen* tioned. Of the four stars formmg tne irregular square m the head, the lower and right* hand one is 5^ N. of Etaoin. It is called Grumitrm, and is of the 3d magnitude. A .cw degrees E. of the square, may be seen, with a little care, eight stars of the 6th magnitude, and one of the 4th, which is marked Omicronf and lies 8° E. of Grumiuin. This group is in the first coil of the Dragon. The second coif is about 13'^ below the first, and may be recognised by meanf of four stars of the 3d and 4th ma^mitudes, so situated as to form a small square, about half the size of that in the head. The brightest of them is on the left, and is marked Delta. A line drawn from Rasfaben through Grumium^ and produced about 14*^, will point it out. A lino drmwo from Lyra through Zi Draconis, and produced 10° further, will point out Zeta, a star of the 3d magnitifde, situated in the third coil. Zeta may otherwise be known, by its being nearly in a line ^vith, and midway between, Etanin and Kochab. From Zeta. the remaining stars in this constellation are easily traced. ISta, IVieta, and Asich, come next ; all stars of the 3d magnitude, and at the distance, severally, of 6^, 4°, and 5° from Zeta. At Asich, the third star from Zeta, the tail of the Dragon makes a sudden crook. Tkuban, Kappa, and Qian- sarj follow next, and complete the tail. Thuhan^ is a bright star of tlie 2d magnitude, 11° from Asich, in a line with, and about midway between, Mizar and the southernmost guard in the Little Bear. By nautical men this star is called the Dragon^s Tail^ and is considered of much importance at sea. It is otherwise celebrated as being formerly the north polar star. About 2,300 years before the Christian era, Thuban was ten times nearer the true pole of the heayens than Cynosura now is. Kappa is a star of the 3d magnitude, 10^ from Alpha, between Megrez and the pole. Mizar and Meerez, in the tail of the Great Bear, form, with Thuban and kappa, in the tail of the Dragon, a large quadrilateral figure, whose longest side ia from Megrez to Kappa. Giansar, the last star in the tail, is between the 3d and 4tn magnitudes, and 6^ firom Kappa. The two pointers will also point out Giansar, lying at the distance of little more than S° from them, and in the direction of the pole. Describe the stars in the first coil of Draco. Describe the stars in the second coU. What is the brightest qf this grmvp coiled, and how mast it be pointed out 7 What is the principal star of the third coil, and how may it be found 1 How else may Zeta Aa knoum? What stars come next to Zeta, in this constellation 7 What stars foUow these 7 Describe Thuban. By what other name is this star known, and for wtot is U celebrated ? When was Thuban within ten minutes of the polel Describe J^nga. WhaUlgm do Misar and Megrez, in the tail of the Great Bear,farmwith TMO^ mA Kms. M t^ Mil t^ihe DragonJ Describe the posUUm of CfUmsar, asidtstthow 1^ iUCTURE OF THE BEAVEN^ L^VA* -■^Here the vast Dragon twines Between tlie Bears, and like a river winds, The Bears, that stili with fearful caution keep, Untinged beneath the surface of the deep." Warton*8 VirgU, O. t lIuTORT.— Whoever attends to the situation of Draco, surrounding, as it doe(L the pole of the Ecliptic, will perceive that its tortuous windings are symbolicu of the oblique course of the stars. Draco also winds round the pole of the world, as if to indicate, in the symbolical language of Egyptian astronomy, the motion of the pole of the Equator around the pole of the Ecliptic, produced by the pre< cession of the heavens. The Egyptian hyeroglyphic for the heav^is, was a serpent^ whose scales denoted the stars. When astronomy first began lo be cal- tlvated in Chaidea, Draco was the polar conotellation. Mythologists, however, give various accounts of this constellation ; by some it is represented as the watchful dragon which guarded the golden apples in the famous garden of the tiesperides,* near Mount Atlas in Africa ; and v«ras slain by Hercules. Juno, who presented these apples to Jupiter on the day of their nup- tials, took Draco up to neaven, and made a constellation of him, as a reward for his faithful services. Others maintain, that in the war with the giants, this dragon was brought into combat, and opposed to Minerva, who seized it in her hand, and hurled it, twisted as it was, into the heavens round the axis of the world, before it had time to unwind its contortions, where it sleeps to this day. Other writers of antiquity say, that this is the dragon killed by Cfadmus, who v^as ordered by nis father to go in quest of his sister Europa, whom Jupiter had ccjrried away ai;d never to return to Phoenicia without her. " When now Agenor had his daughter lost, He sent his son to search on every coast ; And sternly bade him to his arms restore The darling maid, or see his face no more." Hia search, however, proving fruitless, he consulted the oracle of Apollo, and was ordered to build a city where he should see a'heifer stop in the grass, and to call the country Bceotia. He saw ^e heifer according to the oracle, and aa he wished to render thanks to the god by a sacrifice, he sent his companions to fetch water from a neighbouring grove. The waters were sacred to Mars, and {[uarded by a most terrific dragon, who devoured all the messengers. Caomati tired of their seeming delay, went to the place, and saw the monster still feodmc on their fiesh. "Deep in the dreary den, conceal'd from day, Sacred to Mars, a mighty dragon lay. Bloated with poison to a monstrous size ; Fire broke in flashes when he glanced his eyes : * Those who attempt to explain the mythology of the ancient!^:, observe that the Hes- perides were certain persons who bad an Immense number of flocks ; and that the ambiguous Greek word /uhmv^ melon, which sometimes signifies an apple and some* times a sheep, gave rise to the fable of the golden apple of these gardens. The " Hesperian gardens famed of old,'* as Milton obser^s, were so called froua Hesperus Vesper, because placed in the west, under the evening star. Some suppose them to liave been situated near Mount Atlas, in AMca ^ others medntafn that they were the isles ^XMit Cape Veid, whose most westerly point is still called Hesperium Comu, the Horn ef the Hespeiides ; while othess contend, that they were the Canary b^lB2ids. Atlas, said to have been contemporary with Moses, was king ef Mauritania, in the nosih part of Africa, and owner of a thousand flocks of every kind. For refusing hoa* piebltty to Perseus, he vtras changed into the mountain that still bears his name ; and which is 80 high, that the ancients imagined that the heavens rested upon Os swmmH. and, consequently, that Atlas supported the world on his shoulders. Viigfl has thli Idea, where he speaks of " Atlas, whose brawny back 8upp(Mrts the skies ;" and He* ftiod, verse 785, advances the same notion :— "Atlas, so hard necessity ordains. Erect, the ponderous vault of stars sustains. Not far from the Hesperldes he stands. Nor from the load retracts his head or tiands." From this very ancient and whimsical notion. Atlas is represented by artists. Hid in woftcs of mytholocy, as an old man hearing the world on his shoulders. HOMOe it 1% Vm* a collection ofmaps, embracing the wb<4e worl£U Is called an AtUm, T.l LYItA. 181 tiis lowering crest was ^lorkms to behol(^ His shoulders and his sides were scaled with gold; Three tongues he brandish'd when he.charged his Ibes* His teeth stood jaggr in three dreadful rows The Tyrians in the den for water sought, knd with their urns explored the hollow tsuU : From side to side their empty urns rebound, And rouse the sleeping serpent with their sound. Straight he bestirs nim, and is seen to rise ; And now with dreadful hissings fills the slcies, And darts his forky tongues, and rolls his slaring ejes. The Tyrians drop their vessels in the fright^ All pale add trembling at the hideous sight. Spire above spire uprear'd in air he stood, AikI gazing round him, overloolc'd the wood : Then Hoating on the ground in circles rolled ; Then leap'd upon them in a miffhty fold. AH their endeavours and their >iopcs are vain } \ Borne die entangled in the winding train ; Some are devoured, or feel a loathsome death, Swollen up with blasts of pestilential breath.^' Cadmas, beholding such a scene, boldly resolved to avenge, or to share ittlt ikte. He therefore attacked the monster with slings and arroves, and, with ta« nssistance of Minerva, slew him. He then plucked out his teeth, and sowed them, at the command of Pallas, in a plain, when they suddenly sprung up failft •nncd men. "Pallas adest: motaeque jubet supponere terras Viperbs denies, populi ihcrementa futuri. faret : et, Ot presso sulcum patefecit aratro, Spargit humi jtissos, mortalia semina dentes< Inde (fide majtis) glebae csspete moved : Primaque de sulcis acies apparuit hastee Tegmina mox capitum picto nutantia cono . Kzistunt : crescitque seges clypeata virorum." Ovid's Met. Ub. iii. v. lOS. ' ** He sows; the teeth at Pallas's command, And flings the future people from his hand. The clods grow warm, and crumble where he sows ; And now the pointed spears advance in rows ; Now nodding plumes appear, and shinins crests. Now the broad shoulders and the rising oreasts; O'er all the field the breathing harvest swarms, A growing host ! a crop of men and arms 1" Entortaining worse apprehension from the direful ofis^ring than he had done /h>m the dragon himscn; he was about to fly, when they all fell upon each other, and were all slain in one promiscuous carnage, except five, who assisted Cadmus to build the city of Bceotia. ^ LYRA. ' The Harpj — :This constellation is distinguished by one of the most brilliant stars in the northern hemisphere, it is sit- uated directly south of the first coil of Draco, between the Swan, on the east, and Hercules, on the* west; and when on the meridian, is almost directly oyer head. It contains twenty-one stars, including one of the 1st m3^- citude, two of the 3d, and as many of the 4th. By what la the constellaUon of the Harp distinguished J VThere is tt situated? »K the nunber aw) ipagBitadB of .Its stazs? 122 l^ICTURE OP tlie HEAVENS. (aOV 'There Lyra, for the brii^htness of her stars, More than their number eminent ; thrice seven 6he counts, and one of these illuminates Tlie heavens far around, blazing imperia* In the Jirst order." This star, of " the first order, blazing with imperial" lustre, is called Vega, and sometimes Wega; but more frequently it is called I/yra, after the name of the constellation. There is no possibility of mistaking this star for any other. £t is situated 14f ° S. E. of Etanin, and about 30° N. N. E. of Ras Alhague and Ras Algethi. It may be certainly known by means of two small, yet conspicuous stars, of the 5th mag- nitude, situated about 2° a|>art, on the east oi it, and making with it a beautiful little triangle, with the angular point at Lyra. The northernmost of these two small stars is marked £psiton, and the south- em one, Zeta, About 29 S. -E. of Zeta, and in a line with Lyra, is a star of the 4th magnitude,, marked Delta, in the middle of the Harp ; and 49 or 6^ S. ot Delta, are two stars of the 3d magnitude, about 2^ apart, in the garland of the Harp, forming another triangle, whose vertex is in Delta. The star on the east| ' is marked Gamma; that on tlie west. Beta. If a line be drawn from iStania through Lyra, and produced 6° farther, it will reach Beta. litis is a variable star, changing from the 3d to nearly the 5th magnitude in the ^Mtce of a week ; it is supposed to have spots on its surface, and to turn on its axis, like our sim. Gamma comes to the meridian 21 minutes after Lyra, and precisely at the same moment with Epailon, in the tail of the Bagle, 17JP S. of it. The declination of Lyra is about 38|° N. ; consequently when on the meridian, it is but 2° S. of the zenith of Hart* ford. It culminates at 9 o'clock, about the 13th of August. It is as favourably situated to an observatory at Washington, as Rastaben is to those in the vicinity of London. Its surpassing brightness has attracted the admiration of astronomers in all ages. Manilius, who wrote in the age of Augustus, thus alludes to it : — ''Onb, placed in front above the rest, displays A vigorous light and darts surprising rays.'* AatTonomicon, B. i. p. 15. History. — It is generally asserted that this is the celestial Lyre which ApoDo or Mercury gave to Orpheu^ and upon which he played with such a masterly hand, that even the most rapid rivers ceased to flow, the wild beasts of the fure«Ut forgot their wilduess, Snd the mountains came to listen to his song. Of all the nymphs who used to listen to his song, Eurydice was the only one who made a deep impression on the musician, and their nuptials were celebra* ted. Their happiness, however, was short. Aristeeus became enamoured of Eurydice, and as she fled from her pursuer, a serpent, lurking in the grass, bit her foot, and she died of the wound. Orpheus resolved to recover her, or perish in the attempt. With his lyre in bis hand, he entered the infernal regions, and gained admisraon to Pluto. The king of hell was charmed with his strains, tho *'' ' ' ' ■■■■ 111 ■■■■ I H ill 11 iiiMMii f P ■■■■■^a .1^ ■ -II ■ iiM ii^— ^^^^^ What is the name of the principal star? Describe its position. By what means may It be certainbr Imown 7 What are the nmnu ttfthe two amall sHamfarming^ the base nf the trUmerle? Describe the star in the middle qf the Han, and those toUh which U Jbrms another triangle. How are the stars in the base of thU triantlm marked on th* ""•'^ J?2!* ^fpe^y Beta be pointed out? What U there remarkable in the appmr* f"^ ^^ •^*' ^ . W'*?* .<» o««SS <»» tf»^ meridian 7 What is the declinattcn of Ly»7 When dMi It culminate 7 What ancient ppttmeoUowi it >* ^.1 LYBA. 123 -wheel of Izion stopped, die atone of Sujphus Mood atUl, Tutalus fi>ifot hia tbirst, and even the furies relented. IMuto and Proserpine were moved, and consented to restore him Eorydice, provided he forbore loolciDg behind him till he had come to the extremest bor- aers of their dark dominions. The condition was accepted, and Orpheus was already in sight of the upper regions of the air, when he fox^iot, and turned back to look at hib long lost ^urydice. He saw her, but she instantly vanished from Job sight He attempted again to follow her, but was refused admission. From this time, Orpheus sepahUed himself from the society of mankind, which ao offended the Thracian women, it is said, that they tore his body to pieces, and tlirew his head into the Hebrus, still articulating the words Euridice ! Euryoice .* as it was carried down the stream into the JSgean sea. Orpheus was one of the Areonauts, of which celebrated expedition he wrote a poetical account, which la stiu extant. After his death, he received divine honours, and his lyre became one of the constellations. This fable, or allegory, designed merely to represent the power of mnalc fai the hands or the great master jf the science, is similarly described by three of tile most renowned Latin poets. Virgil, in the fourth book of his Georgicsi ttras describee the effect of the lyre: — ''E'en to the dark dominions of the night He took his way, through forests void of light, And dared amid the trembling ghosts to sin^ And stood before the inexorable king. The infernal troops like passing shadows glide, And listening, crowd the sweet musician's side ; Men, matrons, children, and the unmarried maid, The'mighty hero's more majestic shade. And youth, on funeral pilea-before their parent* lal4 B'en from the depths of hell the damn'd advance ; The infernal mansions, noddinSj seem to dance ; The gaping three-mouth'd dog lorffets to snarl; The furies hearken, and their snakes uncurl ; Ixion, seems no more his pain to feel. But leans attentive on his standhig wheel. All dangers past, at length the lonely bride In safety goes, witli her melodious guide." Fytbagoras and his followers represent Apollo plavin^ upon a harp of seven sti ings, Dy which is meant (as appears from Pliny, b. ii. c. Z^Macrobius i. c 19, and Censorinus c. li.) the sun in oonjnnction witn the seven planets ; for they made him the leader of tlrnt septenary chorus, and the moderator of nature, and thought tliat by his attractive force he acted upon the planets in the harmonical ratio of their distances. The doctrine of celestial harmony, by which was meant the music of the Riheres, was common to all the nations of the East. To this divine music Euri- pides beautifully alludes :—" Thee I invoke, thou self-created Being, who gave birth to Nature, and whom light and darkness, and the whole train of globes eiv circle with eternal music."-^ also Shakspeare : — -"Look, how the floor of heaven Is thick inlaid with patines of bright gold ; There's not the smallest orb, which thou behold'e^ But in his motion like an angel sings. Still quiring to the young-eyed cherubim : Buch hannonv is in immortal souls ; But, whilst this muddv vesture of decay Doth grossly close it m, we cannot hear it " The lyre was a famous stringed instrument, much used among the ancientSt tald to have been invented by Mercury about the year of the world 2000 ; though eome ascribe the invention to JubaL (Genesis iv. 21.) It is universally allowed, •hat the lyre was the first instrument of the string kind ever used in Gteece. The different lyres, at various periocfs of time, had from four to eighteen stringa each. The modem Ivre is the Welsh harp The lyre, among painters, is an attribute of Apollo and the Muses. ^ , ^ . j^^ All poetry, it has hern conjectured, was in Its origin lyric ; that 'Si »dapt^?;5 recltatkm or song, rnh lie accompaniment of musfe and dlstlnguisnea uy ine 124 riCTCRE OP TBK HEAVENS. TaVO ottiio^i boAliiess of thought and expression; being at first emf^yed in celebm tiii£ the praises of gods and heroes. , l^slios was the principal seat of the Lyric Muse ; and Terpander, a native of tills inland, who flourished atwut ^0 years B. C, is one of the earliest of the lyric poets whose name we 6nd on record. Sappho, wiwse misfortunes lutve united with her talents to render her name memorable, was bom at Mitylene, the chief city of Lesbos. She w^as reckoned a tenth muse, and placed wuhout con* troversy at the head of the female writers in Greece. But Pin^r, a native of Thebes, who flourished about 500 years B. C, is' styled the prince of lyric poets. To him his fellow-citizens erected a monument ; and when the Lacedemonians ravaged Bceotia, and burnt the capital, the following words were written »ipon the door of the poet : Forbeab to bukk this house. It .was tbb DWBLLnra op Pindar. SAGITTARIUS. The Archer. — This is the l \ath. sign and the tenth con- stellation of the Zodiac. It is situated next east of Scorpio, with a mean declination of 35° S. or 12° below the ecliptic. The sun enters this sign on the 22d of November, but does not reach the constellation before the 7th of December. It occupies a considerable space inihe southern hemisphere, and contains a number of subordinate, though rery conspicu- ous stars. The whole number of its visible stars is sixty- nine, including five of the 3d magnitude, and ten of the 4th. It may be readily distinguished by means of five stars of the 3d and 4th magnitudes, forming a figure resembling a little short, straight-handled Dipper, turned nearly bottom up- wards, with the handle to the west, familiarly called the Milk-Dipper, because it is partly in tlie Milky- Way. This little figure is so conspicuous that it cannot easily be mistaken. It is situated about 33° £. of Antares, and comes to the meridian a few minutes after Lyra, on the 17th of Au- gust. Of the four stars forming the bowl of the Dipper, the two upper ones are only 3° apart, and the lower ones 5°. The two smaller stars forming the handle, and extending westerly about 4|^, and the easternmost one in the bowl of the i)ipper, are all of the 4th magnitude. The star in the end of the handle, is marked Lambda^ and is placed in the bow^ of Ssgittarius, just within the Milky- Way. Lambda may otherwiSfe be known by its being nearly in a line with two other stars about iji° apatt, extending to- wards the S. E. ft is also equidistant from Phi and Delta, with which it mske« a handsome triangle, with the vertex in Lambda. Ahoat 5° above Lambda, and a little to the west, are two stars close together, in the end of the bow, the bright- est of wliieh is of the 4th magnitude, and marked Mu. This star serves to pchil out the winter solstice, being about 29 N. of tlie tropic of Capricorn, and hna than one degree east of the solstitial colure. If a line be drawn from Sigma through Phi, and produced about 6<* &rther to the west, it will point out DeltOj and produced about 3*^ from Delta, it will point out Gamma ; stars of the 3d magnituae, in the arrow. The latter is in tlie point What is the order in the Zodiac, of Sagittarius? How is it situated? When does tij«3 sun appear to enter this constellation) What are its extent and jmpearancel What are the number and raa«niltude of its stars? How may it be readily distinguished f What Is this figure cailed, and why ? W\»ere Is this figure to be found, and when Is It •7n the meridian? How fiir apart are the two up|)er stars in the bowl of the Dipperf How ftur apart are the two lower ones ? Describe the ittars in the handle. Detenbe tka mttUlonef Lambda. How maij Lambda be otherwise hnoum? With what other stio^ does it form a handaonu triangle 7 Dettcribe the position qfMu. Bow nuv DeUa i ^atnma be pointed out if MAT T.J AUTJILA. ET ANTINOUII. 12& of the arrow, and may be known bj means of a small star just abore K, OD the rigr.c This star is so nearly on the sauie meridian with Etanin, in the head i^ Praco, that it cuhninates only two minutes after it A f«iw other conspicuous stars in tliis constellation, forming a variety of ceo- metrical figures,, may be easily traced from the map. ITi^CNiY. — This constellation, it is said, commemorates the lamous Centaur Chiron, son of Philyra and Saturn, who changed himself into a horse, to elude the ieaious inquiries of his wife Rhea. Chiron was famous for his knowledge of music, medicine, and shooting. He taught mankind the use of plants and medicinal herbs ; and inBtructed, in all the pohte arts, the greatest heroes of his age. He taught JEsculapius pbysicj Apollo music ; and Hercules astronomy ; and was tutor to Achilles, JaaoQ, aad ivneas. According to Ovid, he was slain by Hercules, at the river Evenns, for offering indignity to his newly married bride. " Thou monster double ehap'd, my right set free— Swift as bis words, the fatal arrow flew : The Centaur's back admits the feather'd wood, And through his breast the barbed weapon stood ; Which, when in anguish, through the flesh he tore, From both the wounds gush'd forth the spumy gore." . * The arrow which Hercules thus sped at the Centaur, having been difiped In 4ke bkwd of the Lemsean Hydra, rendered the wound incurable, even by the 6ther of medicine himself, and he begged Jupiter to deprive him of immortality. if thua he might escape his excruut that it also turns on its axis. Similar phenomena are observable in Algol, Beta, in the Hare, Delta, in 0^ nheus, and Omicrou, in the Whale, and many others. " Aquila the next, Divides the ether with her ardent wing : Beneath the Siean^ nor £sir from Pegasus^ Poetic Eagle." History.— Aquila, or the Eagle, is a constellation usually joined with Antinoua. Aquila, is supposed to have be*n Merope, a king of the island of Cos, in the Ai^ chipelago, and the husband of Clymene, the mother of Phaeton; this monaich faavmg been transformed into an eagle, and placed among the constellations. Some have imagined that Aqwila was the eagle whose form Jupiter assumed when he carried away Ganymede; others, that it represents the eagle which Drought nectar to Jupiter wtiile he lay concealed in the cave at Crete, to avoid Of what importance Is this star at sea? What Is Its declination? What place does It occupy in the heavens when on the meridian, and when does it culminate? When does it rise acronvcally? Describe the position ofTarazfd. Describe Ihe rata ofatan in the wing of the Eagle. Describe the rmo qf stars xonich mark the youth Antinotu, What stars in the northern wing 1 Describe T^a and Epsilon. Wfien is Epsilon on ihe meridian 7 What long tine olphin, according to some niythologists, was made a con8Cd> lation by Neptune, because one of these beautiful fishes had persuaded the god- dess Amphitrite, who had made a vow of perpetual celibacy, to become the wife of that deity ; but others maintain, that it is the dolphin which preserved the fiunous lyric poet and musician Arion, who was a native of Lesbos, an island ia the Archipelago. He went to Italy with Pcriander, tyrant of Corinth, where he obtained immense riches by his profession. W'shing to revis'it his niflfe country, the sailors of the ship in which he embarked, resolved to murdePRn, and get possession of his wealth. Seeing thera immoveable in their resolution, Arion begged perml8> sion to play a tune upon his lute before he should be pst to death. The melo^ of the instrument attracted a number of dolphins around the ship ; he immedl* ately precipitated himself into the sea ; when one of them, it is asserted, carried him safe on his baclc to Tsnarus, a promontory of Laconia, in Peloi>onnesa»; whence he hastened to the court of Periander, who ordered all the sailors to be crucified at their return. " But, (past belief,) a dolphin's arched back Preserved Arion from his destined vnrack ; Hccure he sits, and with harmonious strains / Rccjuitcs his bearer for his friendly pains." When the famous poe( llcsiod was murdered in Naupactum, a cit^ of JBtoIia, in Gfeece, and lii.s body thrown into the sea, some doljihins, it is said, brought back the floating corpse to the shore, which was immediately recognised by his friends ; and the assa-ssins bcin;; afterwards discovered by the dogs of the de- parted bard, wore put to death, by immersion in the same sea. Tares, said bv some lo have been the founder of Tarentum, now Tarento, in the south of Italy, was saved from shipwreck by a dolphin ; and the inhabitants of that city preserved the raemorv of this extraordinary event on their coin. The natural shape of the dolphin, however, is not incurvated, so that one might ride upon its back, as the poets imagined, but almost straight. When It Is first taken from the water, it exhibits a variety of exquisitely beautiful but evanescent tints of colour, that pass in succession over its bodjr until it dies. They are an extremely swift-swimming fish, and are capable of living along time out of water ; in fact, they seem to delight to gambol, and leap oat of their nwtive element. " Upon the swelling waves the dolphins show Their bending backs ; then swiuly darting go, And in a thousand i\Teaths their bodies show.'* CYGNUS. The Swan. — This remarkable constellation is situated m «he Milky- Way, directly E. of Lyra, and nearly on the same Mention some other stars in the Dolphin, What is the mean declination of the Dol- ^in, and when is It on tlie meridian ? in what part of the heavens is the constellatio C7gnu8 situated t meridian ivith the Dolphin. It is represented on outspread 'win^s, flying down the Milky- Wav, towards the southwesL Tlie principal stars which marK the wings, the body and the bill of Cygnus, are so arranged, as to form a large and vegalar Cross; the upright piece lying along the Milky* Way from N. E. to S. W., while.the cross piece, repre- senting the wings, crosses the other at right angles, from S. E. to N. W. Arided, or Deneb Cygni, in the body of the Swan, is a star of the 1st magnitude, 24^ E. N. E. of Lyra, and SO^' di- rectly N. of the Dolphin. It is the most brilliant star in the constellation. It is situated at the upper end of the cross, and comes to the meridian at 9 o'clock, on the 16th of Sep- tember. Sad'ry U ft star of the 3d magnitnde, 6° S W. <»f Deneb, situated exactly in ths crora, orwhere the i^)rigkt piece intersects the srsss piece> and is about 20^ E. of Lyra. Delta, the principal stw^othe west wing, or arm wf the crosa^ is situated N. W. of Sad'r, at the dista^^f little more than 8°, and is of the 3d magnitnde. Beyond Delta, towards t^^lremity of the wing, are two smaller stars about 6^ apart, and inclining a uHKbliquely to the north : the last of which reanhea nearly to the first coil of Draco. These stars mark tne west wing ; the east wing may oe traced by means of stars Terr similarly situated. Giemih, is a star of the 3d magnituue, in the east vring, just as iar east ef BacPr tak the centre of the cross, as Delta is west of it This row of three equal star% Ikelta, Beui'r. and Gienah, form the bar of the cross, and are eqi^stant from each other, being abowt BP apart Beyond Gienah on the east, at the distance of 99 or 7^ there are two other stars of the 3d magnitnde ; the last of which marku the extremity of the eastern wing. The stars m the necic are all too small to be noticed. There is one, however, in the beak of the Swan, at the foot of the cross, called Albireo. which is of ?he 3d magnitude, and can be seen very plaiolv. It is about 16° S. W. of Sad'r, and •bout the eame distance S. E. of Lyra, with which it makes nearly a right angle. " In the small space between SadT and Albireo," says Dr. Herschel, " the stara in the Milky* Way seem to be clustering into two separate divisions ; each divi- sion containing more than one hundred and gixty-five thousand etars." Albireo bears northerly from Altair abom 20°. Immediately south and south- east of Albireo, may be seen the Fox end GkwsB ; and about midway between Albireo and AHair, there may be traced a line of four or five minute stars, called the Abrow ; the head of which is on the S. W., and can he distinguished by meana of two stars situated close together. According to the British catalogue, this constellation con- tains eighty-one stars, including one of the 1st or 2d mag- nitude, six of the 3d, and twelre of the 4th. The author of the following heautiful lines, says there are one hundred and seven. **Thee, silver Swanj whe^ sBmt, eui overpass) A hundred with eeoem radiant stars compose Thy graceful form : amid the lucid stream Bow is K represented? Wbat remarkable figure Is formed by its principal starsi Describe the pesltton and appearance of Arided, or Deucdi) Cygnl. when does It eul* I&inateat9o>clock7 Deaerihe the position qf S^d^r. Deacrite Dtftm. Whatttareb*- wmd Data? What stan in the east wing 7 What stars form the tar of the croeeJ what stars beyond Gienah on the east 7 Describe the stars in the neck and bOl QTms Bmm. How is the star in the biil situated with respect to Sad^r and Lyraf Whe» Ousters south end southeast (if A iHreo 7 What are the number and aoagnltwU or tM In the «}wan } 180 « PICIX'RE or THE HEATENB. L^VtV Of the fair Milky. Way distinguishM ; atut Adorns the second order, where she c:uta The waved that follow in her utmost track ; This never hides its fire throughout ttie night, And of the restj the moru conspicuous mark Her snowy pinions and refulgent neck.'- — EudoaiOf b. !▼. Astronomers have discovered three variable stars in the Swan. Cht, situated In the neck, between Beta and Sad'r. was first observed to van^ its brightneas^ in 16d6. Its periodical changes of Ufnt are now ascertained to be completed La 405 days. iS'tufr is also changeable. Its greatest lustre is somewhat less than that of a star of the 3d magnitude, and it gi-adually diminishes till it reaches that of the 6th. Its changes are liur from being regular, and, from present observations, they do not seem to recur till after a period often years or more. A third variable star was discovered in the head on the 20th of Jime, ICTti, hj Anthdme. It ap]>eared then to be of the 3d ma^itude, but was so &r diminished in the following October, as to be scarcely visible. In the beginning of ApriL 1671, it was again seen, and was rather brighter than at first After several changes, it disappeared in March, 1672, and has not been observed since. These remarkable facts seem to indicate, that there is a brilliant planetary system in this constellation, which, in some of its revolutions, becomes visible tons. History.— Mytholc^ists give various accounts of the origin of this constella* tkm. Some suppose it is Orpheus, the celebrated musician, wIk), on being miir> dcred by the cruel priestess of Bacchus, was c^HBll into a Swan, and placed near his Harp in the heavens. Others suppose ^^^K swan into which Jupiter transformed himself when he deceived Leda, wiiHHyndarus, icing of Sparta. ISome affirm that it was Cicnus, a son of Neptime, wno was so completely invul- nerable that neither the javelins nor arrows, nor even the blows or Achillea^ ia - furious combal, could make any impression. "Headlong he leaps firom off his loftv car, And in close fight on foot renews the war ; — . But on his fiesh nor wound nor blood is seen, The sword itself is blunted on the sUn." But when Achilles saw that his darts and blows had no effect on him, he tin- mediately threw htm on the ground and smothered him. While he was sttemp^ Ing to deq)oil him of his armour, he was suckienly changed into a swan. ^ "With ea^er haste he went to strip the dead ; The vanisli'd bodv from his arms was fled. His seagod sire, V immortalize his fimie, Bad tum'd it to a bird that bears his name." According to Ovid this constellation took its name from Cygnna^ a relative of Phaeton, who deeply lamented the untimely &te of that youth, and the melai^ choly end of his sisters, who, standing around his tomb, wept themselves into ioolars. "Cicnus l^eheld the nymphs transform'd allied To their dead brother on the morial sioe, In friendship and affection nearer bound; He left the cities, and the realms he own'd, Through pathless fields, and lonely shores to range f And woons made thicker by the sisters' change, Whilst here, within the dismal gloom idone, The ij^elancholy monarch made his moan : His voice was lessened as he tried to speak, And issued through a long-extended neck : His hair transforms to down, his fingers meet In skinny films, and shape his oarv feet ; From both his sides the wings and feathers break : And from his mouth proceeds a blunted beak : '* All Cicnus now into a swan was turn'd." — Ovid'a Met. h. iL What variable stars hav*i autronomers discovered in this constettation 7 Which ^ then toasjlrst discovered to be variable in iS86 i /n iohat period are its pertodioiU chaittm of light completed? Describe the appearance qf Sad'r. tfeecrtte the 01*4 049 covered in tCTO. niua do these remarkable jtcts iniieate 7 V.J CAPHlCOIUfUa HI Vh)Bil, also, fai Che 10th book of hii iEneldi aUttdes to tha Mine (abto >- '*ForCicnas loved unhappy Phaeton, And sung his loss in poplar groves alono^ Beneath the sister snaaes to sooth his gnef ; Heaven heard his song, and hasten'd his relief; And changed to snowy plumes his hoary Iiaif, And wing'd his flight to sing aloft in air." Of all the feathered race, there is no bird, perhaps, which makea so beaxttJfVil and majestic an appearance as the swsua. Almost every poet of eminence has taken notice of it. The swan has, probably, in all ages, and in every country where taste and elegance have been cultivated, been considered as the emblem of poetical dignity, purity, and ease. By the ancients it was consecrated to ApoUa ana the Muses ; they also entertained a notion that this bird foretold its own en4 and sang more sweetly at the approach of deaths " She, like the swan Expiring, dies in melody."-^^«cAy{u«. '*Bo on the silver sti'eam, when death is nigh, l^e mournful swan sings its own elegy.'' — Ovidf Tristiib CAPRICORNUS* TsE Goat. — This u the tentk sign^ and eleventh constel- lation, in the order of the^ZodiaC) and is sit^ted south of the Dolphin, and flext east of Sagittarius. Its mean declination is 20® sotttb',.and.it3 mean ri^ht ascension, 310°. It is there- fore on the meridian about the 18th of September. It is to be observed that the first point of the sigh Capricorn, not the constellation^ marks the ^uthem tropic, or winter solstice. The sun, therefore, arrives at this point of its orbit the 21st of December, but does not reach the constellation Capricorn until the 16th of January. The sun, having now attained its utmost declination south, after remaining a few days apparently stationary, begins once more to retdtce its progress northwardly, affording to the wintry latitudes of the north, a grateful presage of returning spring. At the period of the winter solstice, the sun is vertical to the tropic of Capricorn, *and the southern hemisphere enjoys the same light and heat;ifhich the northern hemisphere en- joys on the 21st of June^ when tfie sun is vertical to the tropio' of Cancer. It is, at this period, mid-day at the south pole, and nudnight at the north pole. The whole nt(mber of stars in this constellation is fifty one 5 none of which are very conspicuous. The three largest are only of the 3d magnitude. There is an equal numbet of the 4th. Wliere is Caprlcornus situated I What are its mean right ascension and declinatlonf When is the main body of the constellation on the meriaian ? When does the son enter the aibgny and when the tonsteUation Capricorn? Does the sun ever extend beyond tide point into the southezn hemisphere > What is the position of the sun with tf niect te the tropic of Capricorn, at the winter soIsUce, and what are the swons to tiie two hemispheies ) What axe the number and magnitude of tbe stars in tlda caai> tteUatlont The head of Capricorn may be recognised by means of Uvo stars of the 3d magnitude, situated a little more than 2^ apart, called Gitdi and DabUu They are 28^ from the Dol^ phm, in a southerly direction* Giedi is the most northern star of the two, and is double. If a line be drawn from Lyra through Altair, and produceil about 23^ farther, it will point out the head of uapricom. These two stars come to the meridian the 9th of September, a few minutes after Sad'r, in Cygni. A few other stars, of inferior note may be traced out by reference to the maps. The sign of the Croat was called by the ancient orientai ists the " Southern gate of the Sun," as Cancer was denom- inated the " Northern gate." The ten stars in the sign Ca • pricorn, known to the ancients by the name of the " Tower of Grad," are probably now in the constellation Aquarius^ History.— Capricomus is Said to ^e Pan, or Bacchus, who, with some odyer tieities were feasting near the banks of the Nite. when suddeoly the dreadAU giant T^phon came upon them, and compelled tnem all to assume a difilsrenC shapei m order to escape hts fury. vOvid relates, "How Typlion, from the conquer'd skies, pursued Their routed godheads to the seven-moutiiM flood: Forced every god, (his fury to escape,) Some beastly form to take, or earthly shapes Jove (sings ihe bard) was chan^'d into a nxa^ From whence the horns of Lybian Ammon came» Bacchus a goat, Apollo was a crow , PhcRbe a cat; the wife of Jove a coW) Whose hue was whiter than the falling snow Mercury lo a nasty Ibis turned — WhUe Venus from a fish protection cravns, And once more plimges in her native waves." Ol this occasion it is further related that Bacchus^ or Pan, led the way and plunged into the Nile^ and that the part of his body which was under the water, assumed the form of a fish, and the other part that of a goat ; and that to pre serve the memory of this frolic, Jupiter made him into a constellation, in hit metamorphosed shape. Some say that this constellation was the goal Amalthea, who supported the in lant Jupiter with her milk. To reward her kindness, the father of the godt placed ner among the constellationsj and gave one of her horns to the nymphs who had tat^n care of him In his infantile years. This gift was ever after called the horn vf plenty'; as it possessed the virtue of imparting to the holder whaC^ ever she desired.* The real sense of this fable, divested of poetical embellishment, appears to be this ; that in Crete, some say m Lybia, there was a small territory shaped very much like a budlock's horn, and exceedingly fertile, which the king presented to his daughter Amalthea, whom the poets feigned to have been Jupiter's nurse. "The bounteous Fan," as he is stvied by Milton, was the god of rural scenery shepherds, and huntsmen. Virgil thus addresses him : — * On this account the Latin term Cornucopia, denotes plenty, or abundance of good things. The word Amalthea, when used figuratively, has also the same meaning. How may it be recognised) How are Giedi and Oabih situated with respect to the Dolphin? How are these two stars distinguished from each other, and what is thelx liosition in respect to the Eagle i When are they on our meridian? What were tbt Migna Capricorn and Cancer originally called 7 Where are the ten stars, known to tte ancients by the name of the *' Tower of Gad." now tp be fi>uiul i MAP tl ) l*EC\dUS9. lis 'And tbou, the shepherd's taltelary go where to be seen, that kind of fear which often seizes men, and which is (mljf ideal or imaginary, has received from him the name dTPatue. CHAPTER XII. 0IR£CnONS FOR TRACtNO THfi CONSTELLATIONS WHICH ARE OM THE MERIDIAN IN OCTOBER. PEGASUS. The Flying Horse.— This constellation is represented in an inyerted posture, with wings. It occupies a large space in the heavens, between the Swan, the Dolphin and the Eagle, on the west, and the Northern Fish and Andromedaj on the east. Its mean right ascension is 340*^, or it is situa* ted 20° W. of the prime meridian. It extends from the equinoctial N. 35°. Its mean length E. and W. is about 40°, and it is six weeks in passing our meridian, yiz. from the 1st of October to the 10th of November. We see but a part of Pegasus, the rest of the. animal, being, as the poets imagined, hid in the clouds. Jt is readily distin^shed from all other constellations by «neans of four remarkable stars, about 15° apart,' forming the ligure of a square, called the square of Pegasus. The two western stars in this square come to the meridian about the 23d of October, and are 13° apart. The northern one, which is the brightest of three triangular stars in the martingale, is of the 2d magnitude, and is called Scheat, Its declination is 26%° N. Markab, also of the 2d magnitude, situated in the bead of the wing, is 13^ S. of Scheat, and passes the meri- dian 11 minutes after it. * Psdes, &e femide deity coxzesxKKicUng to Pan, wis the eoddess of sheepfolds and •f postoxes among the Romans. Thus Vizgil :— " Now, sacred Pales, in a lofty strain* I sing the rural honours of thy reign.*' The ahepberda offered to thia goddess milk and honey, to gain her protection over e»eir flocks. She is represented^ as ui old woman, and was worshipped with graat aolemnity at Rome. Her festivals wtiich were called PaUlia, were celebrated on tto IHh of April, the day on which Romulus laid the foundations of the city. » ■ ■ ■ . ■ I ■ How is Pegasus representedl What space and i>osltlon does it occupy in the hea- ena J What axe the distance and direction of its centre from the prime meri^anf What are Its mean length and breadth j How long Is it in passing yy meridian f Wben *»«• It pass the meridian 1 How Is this constellation distinguished ftora aU KiMMi f Descrlba the two aiBrs -which form tha west aide of the squaie ? 12 134 PICTURE OF TH£ HEAVENSL I OCT The two stars which fonn the eastern side of the square, come to the meridian about an hour after those in the western. The northern one has already been described as Alpheraiz in the head of Andromeda, but it also belongs to this constel* lation, and is 14<^ E. of Scheat. 14° S. of Alpheratz, is Al- genib, the last star in the wing, situated 16J° E. of Markab. Algenibf in Pegasus, Alpheraiz^ in Andromeda, and Cavh in Cassiopeia are situated on the prime meridian^ and point out its direction through the pole. For this reason, they are sometimes called the three guides. They form an arc of that great circle in the heavens from which the distances of all the heavenly bo- dies are measured. It is an arc of the equinoctial colure which passes through the vernal equinox, and which the sun crosses about the Slst of Afarch. It !% la astronomy, what the meridian of Greenwich is in geography. If the scm, or a planet, or a star, be said to have so many degrees of right ascension, it means that the sun or planet has ascended so man^ degrees from this prime incridiaiL Enif^ sometimes called Enir^ is a star of the 3d magnitude in the nose of Pe- gasus, about 20° W. 6. W. of Alarlcab, and ^lalfway between it and the Dolphin. About \ of the distance from Markab towards Eni^ but a little to the S., there is a star of tlie 3d magnitude situated in tile neck, whose letter name is Zeta. The loose cluster directly S. of a line joining Enif and Zeta, forms the head of Pe- gasus. In this constellation, there are eighty-nme stars visible to the naked eye, of which three are of the second magnitude and three of the third. HisTORT.— This, according to fable, is the celebrated horse which sprung from the blood of Medusa, after Perseus had cut off her head. He received his name according to Ilesiod, from his being bom near the sources C^^^") Pege) of the ocean. According to Ovid, he fixeii his residence on Mount Helicon, where bj striking the earth with his foot, he raised the fabled fountain called Ilippocrene. He became the favourite of the Muses ; and being tamed by Neptune or Bli- nerva, he was given to Bellerophon, son of Gkiucus, kin^ of Ephyre, to aid him in conquering the Cliimeera, a nideous monster that contmually vomited flames. This monster had three heads, that of a lion, a goat, and a diragon. The fore parts of its body were those of a lion, the middle those of a goat, and the hinder those of the dragon. It lived in Lycia, of which the top, on account of its deso- late wilderness, was the resort of lions, the middle, which was fruitful, was c0t< ered with goats, and at the bottom, the marshy ground abounded with serpents. Bellerophon was the first who made his habitation upon it. Plutarch thinks the Chimsera was the captain of some pirates who adorned their ship with the images of a lion, a goat, and a dragon. After the destruction of this monster, Bellerophon attempted to fly up to hea^ vcn upon Pegasus ; but Jupiter was so displeased at this presumption, that he sent an insect to sting the horse, which occasioned the melancholy fall of his rider. Bellerophon fell to the earth, and Pegasus continued hi» flight ap to hesr ven, and was placed by Jupiter among the constellations. "Now heav'n Ms farther wand'rhtg flight confineif^ Where, splendid with his num'rou& stars, he shiaes." Ovid^sFasH. EaUULUS, VEL EaUI SECTIO. The Little Horse, or the Horse's Head. — This Aste- nsxn, or small cluster of stars, is situated about 7° W. of Enif, in the head of Pegasus, and about halfway between it ^Describe the two on the" east side. What is the name of the star in the N. B. coicer of the square) In the 8. E. comer? In the S. W. comeri In the N. W. comer? De* aerihe the position and tnagrnttude af JBwW: What is the whole number of stars In KS??*.I?5 * T !2.' ' *® magnitude of the principal ones ? Describe the sltuatf a of tik» »• Littls Honr HAP n ] AQUARIUS. 135 and the Dolphin. It is on the meridian at 8 o'clock, on the 11th of October. It contains ten stars, of which tlie four principal are only of the 4th magnitude. These may be readily distinguished by means of the long irregular square which they form. The two in the nose, are much nearer to- gether than the two in the eyes ; the former beiug 1° apart, and the latter 2^^. Those in the nose are uppermost, being 4° N. of those in the eyes. This figure also is in an inverted position. These four stars are situated 10° or 12° S. E. of the diamond in the Dolphin's head. Both of these clusters, are noticeable on account of their figure rather than their brilliancy. History.— This constellation is supposed to be the brother of Peeasu% named Ctieris^ given by Mercury to Castor, who was so celebrated for his skiU in th« management of horses ; others take him to be the celebrated horse which Nep- tune struck out of the earth with his trident, when he disputed witli Minerva for superiority. The head only of Celeris is visible, and tlus, also, is represented in an inverted position. AaUARIUS. The Water-Bearer. — This constellation is represented by the figure of a man, pouring out water from an urn. It is situated in the Zodiac, immediately S. of the equinoctial, and bounded by the Little Horse, Pegasus, and the Western Fish on the N., the V/halc on the E., the Southern Fish on the S. and the Goat on the W. It is now the 12th in order, or last of the Zodiacal constellations; and is the name of the 11th sign in the ecliptic. Its mean declination is 14° S. and its mean right ascension SSS^', or 22 hours, 20 min. ; it being 1 hour and 40 min. W. of the equinoctial colure ; its centre is, therefore, on the meridian the 15th of October. It contains one hundred and eight stars ; of which the four largest are all of the 3d magnitude. "His head, his shoulders, and his lucid breast, Glisten with stars ; and where his urn inclines Rivers of light brighten the wat'17 track." The northeastern limit of Aquarms may be readily distin- fi^shed by means of four stars of the 4th magnitude, in the hand and handle of the urn, so placed as to form the letter Y, very plainly to be seen, 15° S. E. of Enif, or 18° S. S. W. of Markab, in Pegasus ; making with the two latter nearly a right angle. When is It on the meridian? What is the whole number of its stars 7 What is the magnitude of the principal ones? How may the principal stitrs be distinguished) How are the two in tiie nose distinfniished ftrom the two in the eyes? What are their distance and direction from the Dolphin? On what account are these clusters noticea- Wei How is Aquarius represenletl? Where is it situatoji? What is its present older among the constellations of the Zodiac? What are its right as«;enslon and declination} ^Fhat is the whole number of its stars ? What is the magnitude of the principal ones} How may the N. E. limit of A.quarhi8 be readily disUngulshed? What are tlte distance and direction of this letter Y, from Markab and Enlf, in Pegasus 7 196 t-lCTURC OF THE UEAVENS. | O^JT* About 4^0 W. of this figure is El MeUk, a star of the 3d majmituOe. in the B. ■hoaliler, and the principal one in this constellation. 10*^ B. W. of El MeOk, iB fenother star of the same magnitade, situated hi the W. shoulder, called Scutes SawL Ancha of the 4th magnitude, is in the right side, 8° S. of El Mellk. 9° E. of Ancha, is another star of the 4m magnitude, whose letter name is Lambda. Scheat. of the 3d magnitude, lying oeiow the knee, is situated 8i^^ S. of Lamln da; and 14° S. of Scheat, the briUiant star FomalhauL* of between the let and 2d magnitudes, terminates the cascade in the mouth of tiie Southern Fish. This star is commmi to both these constellations, and is one of Uiose from which tho lunar distance is computed for ascertaining the longitude at sea. It culminates at 9 o'clock on the 22a of October. Fomalhaut,* Deneb Kaitos, and Alpha in the head of the Fhosnix, make a larse triangle, whose venex is in Deneb Kaitos. Those two stars of the 4th magnitude, situated 4° S. of Sad os Saud, and nearly the same distance from Ajicha, are in the tail of Capricorn. They are about 2^^ apart The western one is called Deneb Algedi. The rest of the stars in the cascade are quite small ; they may be traced from the letter y, in the urn, in a southeasterly direction towards the tail of Cetus, from which the cascade suddenly bends off near Scheat, in an opposite courae^ and finally disappear^} in the mouth of the Southern Fish, 2fP S. of Y. History.— This constellation is the 'famous Ganymede, a beautiful youth of Phrygia, son of Tros, king of Troy, or, according to Lucian, son of Dardanus. He was taken up to heaven by Jupiter as he was tending his fether's flocks on Mount Ida, and became the cupbearer of the gods in place of Hebe. There are various opinions, however, among the ancients respecting its origin. Some sup> pose it represents Deucalion, who was placed among tlie stars after the celebra* ted deluge ofThessaly, ISOO years before the birth of our Saviour; while otheit think it designed to commemorate Cecrops, who came from Egypt to Greece, founded Athens, established science, and mtroduced the arts of polished life. The ancient Egyptians supposed the setting or disappearance of Aquarius caused the Nile to rise, by the sinking of his urn in the water.— In the Zodiac of the Hebrews, Aquarius represents the tribe of Reuben. PISCIS AUSTRALIS, VEL.NOTiUS. The Southern Fish. — This constellation is directly S. of Aquarius, and is represented as a fish drinking the water which Aquarius pours from his urn. Its mean declination is 31° S. and its mean right ascension and time of passing the meridian are the same as those of Aquarius, and it is seen on the meridian at the same time ; viz., on the- 15th of October. It contains 24 visible stars, of which one is of the 1st magni- tude or between the 1st and 2d, two are of the 3d, and five of the 4th. The first and most beautiful of all is Fomalhaut^ situated in the mouth. This is 14° directly S. of Scheat in Aquarius, and may be seen passing the meridian low down m the southern hemisphere, on the 22d and 23d of October. * Pronoanced Fo^morlo. What is the name of the principal star in this constellation? What U its position? VHuu star in the W. shotuderl Describe the situation nf Ancha. What is the posi- tion of Bcheax and Fomathata 7 To what constellations is Fomalhaut commrni 7 Cf what nautical importance is it? When does it culminate? With what other ^arw does it form a large triangle 7 How may you trace the stars in the cascade 7 Describ(» She situation and appearance of the Southern Pish. What are its mean right ascensioii and decliuatlon} when is It on the meridian? What is the whole nunUier of its stars? '''**?Ul.W® magnitude of Its principal ones? What are the name and position of the most brilliant star In the constellation ? When and where does it pass Ube meridian? YAUlABriE AND DOUBLE STARS, &e. ISH Cttf position in the heavens has heen determined with the peatest possible accuracy, to enahle navigators to find their longitude at sea. The mode of doing this cannot be explained here. The problem is one of soma diflicuity. It consists in finding the angular cUstance between some star whuM position is well known, and the mooq when she is passing near it ; also, th« altitude of each, at the same instant, with good sextants. These data furnish the elements of a spherical triangle, the solution df which, after various intricate corrections, is made to result in the longitude of the given place. — See note to Arieties. In 1714, the British Parliamcnt'bfiered a reward 0110,000 pounds ster* )in^, to any man wlio shouid discover a method of determining the longitude within 1^, or 60 geographic miles of the truth ; 15.000 pounds to the man who should find it within 40 miles, and 20,000 pounds, if found within 30 miles. These rewards in part have been since distributed among eminent mathematicians, in Europe, agreeably to the respective merits of their discoveries. If isTORT. — ^This constellation is supposed to have taken its name from the transformation of Venus into the shape of a fish when she fled, terrified at the horrible advances of the monster Tvphon, as we have related in the mytholofX of the Fishes.— m panicu- '""'• 13* 138 DOUBLE STARS. nerer been seen since. (^See a more particular account of ihis phenomenon, page 40.) Another instance of the same kind was observed in 1604^ when a star of the first magnitude suddenly appeared in the nght foot of Ophiuchus. It presented, like tne former, all the phenomena of a prodigious name, being, at first, of a dazzling white, then of a reddish yellow, and^ lastly, of a leaden pale- ness; in which its light expired. These instances prove that the stars are subject to great physical revolutions. — Page 41. A great number of stars have been observed whose light seems to undergo a regular periodic increase and diminution. They are properly called Variable Stars. One in the WhcUe has a period of 334 days, and is remarkable for the magnir tude of its variations. From being a star of the second mag^ nitude, it becomes so dim as to be seen with difficulty througi& powerful telescopes. Some are remarkable for the shortness of the period of their variation. Algol has a period of between two and three days ; Delta Cephei, of 5J days ; Beta L/yrrlt9r have established the truth of this theory? What rates of motion did they detect In these Moary systems ? What other interesting phenomena, indicating a »ww2»» SgJ- vtion, did they discover? What is the most TemarkaJ>le instance of "»1»J2**I,«^*; ttOB tMime other instances. Are these revolving stars of a planetaiy nature T w wi«« vaturearR they? 140 DOUBLE STARS. ets from thmr primaries, bear to their distances from the &Uk itself. (/,',,:■ The examination of double stars was first undertaken by tlie late Sir Williaa Berachel, with a view to the question of parallax. His attention was, however flcon arrested by the new and unexpected plienomena which these bodies pre •ented. Sir WUliam observed of them, in all, 2400. Sir James South and Her ■chel have given a catalogue of 3B0 in the Transactions of the Royal Socictv, fo. IBSk. and South adkled 45^ in 18S6. Sir John Herschel, in addiliun to the above published an account of 1000, before he left England for the Cape of Good Hopej where he is, at the time we write, pushing his discoveries in the southern hem- {sphere with great perseverance and success. Professor Struve, with the gieat Dorpat telescope, has given a catalogue of 3^063 of the most remarkable of thees ■tars. The object of these catalogues is not merely to fix the place of the star within such limits as will enable us easily to discover it at any future time, but also to record a description of the appearance, position, and iqutual distances, of the individual stars composing the system, in order that subsequent observers may have the means of detecting their connected motions, or any changes which they may exhibit Professor Struve has also taken notice of 32 triple stars, among which No. 11 of the Unicom^ Zela of Cancer, and Zi of the Balance, appear to be ternary systems in motion. Quadruple and quintuple stars have likewise been observed, which also appear to revolve about a common centre of gravity ; in short, every region of the heavens furnishes examples of these curious phe- nomena. Colour of the Stars, — M^ny of the double stars exhibit the curious and beautiful phenomenon of contrasted colours^ or complimentary tints. In such instances, the larger star is usually of a ruddy or orange hue, while the smaller one ap- pears blue or green, probaWy in virtue of that general law of optics, which provides, that when the retina is under the in- fluence of excitement by any bright, coloured light, feebler lights, which seen alone would produce no sensation but that of whiteness, shall for the time appear coloured with the tint complimentary to that of the brighter. Thus, a yellow colour predominating in the light of the brighter star, that of the less Dright one, in the same field of view, will appear blue ; while, if the tint of the brighter star verge to crimson, that of thts other will exhibit a tendency to OTeen — or even appear a vivid green. The former contrast is beautifully exhibited by lota^ in Cancer ; the latter by Almaack, in Andromeda — both fine double stars. If, however, the coloured star be much the less bright of the two, it will not materially afiect the other. Thus, for instance. Eta Cassiopeise exhibits the beautiful combina tion of a large white star, and a small one of a rich ruddy purple. It is not easy to conceive what variety of illumination two suns — a red and a green, or a yellow and a blue one — must afford to a planet revolving about either ; and what charmini^ WhatbeautiHi! and curious phenomenon has been observed, as It regards the colour of double sfsrs } Explain how these colours are usually contrasted. Mention an eoc- ample of this phenomenon. How, If the coloured star be much the less bright of the two. 2*11 the other be affected ? Give an instance. What may be the tiffeet of such a ^ciety of colot** in solar light? ^ y CLUSTERa. I A I contrasts and grateful yicissiiudes — ^a red and a grern dav, for instance, alternating with a white one and with darhiess — might arise from the presence or absence of one or the otl;er, or both, above the horizon. Insulated stars of a red colour, almost as deep as that of blood, occur in many parts of thii Keavens, but no green or blue star (of any decided hue) has, we believe, ever been noticed, unassociated with a companion brighter thian itself. Clusters. — ^When we cast our eyes over the concave sm- face of the heavens in a clear night, we do not fail to observe that there are, here and there, groups of stars which seem to be compressed together more densely than those in the neigh- bouring parts ; forming bright patches and clusters. There is a group called the Pleiades, in which six or seven stars may be noticed, if the eye be directed f«ti upon it ; and many more if the eye be turned carelessly aside, while the at- tention IS kept directed* upon the group. Telescopes show fifty or sixty large stars thus crowded together in a very mod- erate space, and comparatively insulated from the rest of the heavens. Rheita amrms that he counted 200 stars in this small cluster. The constellation, called Coma Berenices, is another group, more diffused, and consisting of much larger stars. In the constellation Cancer, there is a nebulous cluster of very minute stars, called Pr^Bsepe, or the Beehive, which is Bumciently luminous to be seen oy the naked eye, in the ab- sence of the moon, and which any ordinary spyglass will re- sblve into separate stars. In the sword-handle ot Perseus, also, is another such spot, crowded with stars. It requires, however, rather a better telescope to resolve it into individuau stars. These are called Clusters of Stars, Whatever be their nature, it is certain that other laws of aggregation subsist in these spots, than those which have determined the scattering of stars over the general surface of the sky. Many of them, indeed, are of an exactly round jfigure, and convey the idea of a globular space filled full of stars, and constituting, in it- self, a family or society apart, and subject only to its own internal laws. " It would be a vain task," says the younger Herschel, " to »— »— ■^^— ■ ■ ■ * " It Is a very remarkable fact," says Sir John Hersebel, " that the centre of the ▼isual organ is by for less sensible to feeble impressions of light, than Uie exterior poitions of the retina."— J«t. p. 398. m ■' Are indlvidua] stars of a deep colour ever found separate ftom <>tl»«"' .IIJ^ "• clusters ofstarsi Mention some instance. nescribeiL MenUon some other i^ Describe the posiUon and appearance of Praaepe. Describe ««iy ©the* ©iwMa^niej yon nay reco*UecL What are the constitnUon and tone «£ *«2*tS£BBBtrSl ttie younger Herschel say of the number of stars wWch compose tBAse duswrsi Itt NEBULA. attempt to count the stars in one of these globular clusters. They are not to be reckoned by hundreds ; for it would ap- pear that many clusters of this description must contain, at least, ten or twenty thousand stars, compacted and wedged together in a round space, not more than a tenth part as large as that which is covered by the moon. 4. Nebul£. — The Nebulae, so called from their dim^ cloudy appearance, form another class of objects which furnish mat- ter for curious speculation, and conjecture respecting the for- mation and structure of the sidereal heavens. When exam- ined with a tele3C0{>e of moderate powers, the greater part of the nebulae are distinctly perceived to be composed of little stars, imperceptible to the naked eye, because, on account of their apparent, proximity, the rays of light proceeding from each are blended together, in such a manner as to produce only a confused luminous appearance. In other nebulae, however, no individual stars can be per- ceived, even through the best telescopes; and the nebulae exhibit only the appearance of a self-luminous or phosphores- cent patch of gaseous vapour, though it is possible that even in this case, the appearance may be owing to a congeries of stars so minute, or so distant, as not to afford, singly, sufficient light to make an impression on the eye. In some instances a nebula presents the appearance of a faint luminous atmosphere, of a circular form, and of large extent, surrounding a central star of considerable brilliancy. One of the most remarkable nebulae is in the sword-hanole of Orion. It is formed of little flocky masses, like wisps of cloud, which seem to adhere to many small stars at its out- skirts. It is not very unlike the mottling of the sun's disk, but of a coarser grain, and with darker intervals. These wisps of light, however, jjresent no appearance of being composed of small stars ; but in the intervals between them, we fancy that we see stars, or that, could we strain our sight a little more, we should see them. These intervals may be compa- red to openings in the firmament, through which, as through a window, we seem to get a glimpse of other heavens, and brighter regions beyond. — Page ^, Another very remarkable nebula is that in the girdle of An- dromeda, which, on account of its being visible to the naked eye, has been known since the earliest ages of astronomy. It is often mistaken for a comet, by tliose unacquainted with the ••.3JJ2L"ir®.iJi^?®5*^",5^ ''^^l^' Describe the usual appearances of nebula, as seen SJ2?^«?»H?5if®^;K What other appearance do nebulae sometimes exhibit J Mention {SSfi-HS^*®" '^*®i?<*^', remarkable nebula. Describe the one In the swonf- iwndle of Orion. Describe the one which is fai the girdle of Andn)raeda. ■«^""- NEBUUE. 143 aearens. Marius, who noticed it in 1612, describes its ap- (learance as that of a candle shining through horn ; and the resemblance is certainly very striking. Its form is a long oval, increasing, by insensible gradations of brightness, from the circumference to a central point, which, though very much brighter than the rest, is not a star, but only a nebula in a high state of condensation. No power of vision hitherto di- rected to this nebula has been able to resolve it into the least appearance of stars. It occupies an area comparatively large —equal to that of the moon in quadrature. — This nebula may be considered as a type, on a large scale, of a very numerous class of nebulae, of a round or oval figure, increasmg more o less in density towards the centre. Annular nebulcB also exist, but are among the rarest ob- jects in the heavens. The most conspicuous of this class, is to be found exactly halfway between the stars Beta and Gamma Lyras, and may be seen with a telescope of moderate power. It is small, and particularly well defined ; appearing like a flat oval ring. The central opening is not entirely dark, but is filled with a faint, hazy light, uniformly spread over it, like a fine gauze stretched over a hoop. Planetary nebulce are very extraordinary objects. They have, as their name imports, the appearance of planets, with round or slightly oval disks, somewhat mottled, but approach- ing, in some instances, to the vividness of actual planets. Some of them, upon the supposition that they are equally dis- tant from us with the stars, must be of encMrmous ma^itude. That one, for instance, which is situated in the left hand of Aquarius^ must have a volume vast enough, upon the lowest computation, to fill the whole orbit of Herschel I The nebuloe furnish an inexhaustible field of speculation and conjecture. That by far the larger number of them con- sists of stars, there can be little doubt ; and in the intermina- ble range of system upon system^ and firmament upon firma- ment, which we thus eaten a glimpse of, the imagination is bewildered and lost. Sir William Herschel conjectured that the nebulae might form the materials out of which nature elabomted new suns and systems, or replenished the wasted light of older ones. But the little we know of the physical constitution of these sidereal masses, is altogether insumcient to warrant such a conclusion. Of what class of netmls may this be considered as a type? What other speetes of nebuls eadst In the heavens? Describe the most conspicuous of this class. Vfhrt oOier species of nebuln axe more rarely foundf Describe the appeaxance of planetav nebulsB. What do wi» know in regard to their roafnituJel How Jawre must tlie onOe which is sttuateti in aic left hand of Aquarius j^What «lld Sir WiUl»«n Herschel ccr- toeiure as to the use of the nebulas i Have we Ihcts sufficient to wsirwt sucn a oo^ kctuTOf )44 VIA LACTCA, OH t**^*" ^"t CHAPTER XIV. ' • "V I. VIA LACTEA. ^ "Throoghout the Gftlaxy's extended line, UnnainDer'd orbs in gay confusion shine : Where every Btsu* that gilds the gloom of night With the faint tremblings of a distant light, Perliaps illumes some system of its own, With the strong influence of a radiant sun." — Mt9. Cartef ^ There is a luminous zone or pathway of singular white* ness, varying from 4<^ to 20^ in width, which passes quite round the heavens. The^ Greeks called it Qalaxy, on ac- count of its colour and appearance : the Latins, for the same reason, called it Via Lactca, which, in our tongue, is Milky Way. Of all the constellations which the heavens exhibit to out view, this fills the mind with the most indescribable gran- deur and amazement. When we consider what unnumbered millions of mighty suns compose this cluster, whose distance is so vast that the strongest telescope can hardly separate their mingled twilight into distinct specks, and that tlie most contiguous of any two o\ them may be as far asunder as our sun is from them, we fall as far short of adequate language to express our ideas of such immensity, as we do of instru^ ments to measure its boundaries. It is one of the recent achievements of astronomy that has resolved the Milky-Way into an infinite number of small stars, whose confused and feeble lustre occasions that pe- culiar whiteness which we see in a clear evening, when the moon is absent. It is also a recent and well accredited doc- trine of astronomy, that all the stars in the universe are ar- ranged into clusters, or groups, which are called Nebulj:: qj Starry Systems, each of which consists of many thousands of stars. The fixed star which we call our Sun, belongs, it is said, to that extensive nebula, the Milky- Way ; and although ap* parently at such an immeasurable distance from its fellows, IS, doubtless, as near to any one of them, as they are to one another. Of the number and economy of the stars which compose this group, we have very little exact knowledge. Dr. Her- schel informs us that, with his best glasses, he saw and — - I ' What do you understand by the Milky-Way 1 By what different names Is it called Why does the contemplation of this constellatton nil the mind with ideas of grandeur ud amazementi What causes the whiteness of the Bfflky- Way 1 Into what axe all the Stan in the, universe aminged? To what nebula does the sun tekmc, and wiMit Is inobobly its distance (torn its fellows! What knowMlM have we of thenuorimr — Monoovoftlie stars in this group? ^^ MAP V1II.J MILKY-WAY. 14^ coanted 588 stars in a single spot, without moring Ms tele* scope ; and as the gradual motion of the earth carried these out of view and introduced others successively in their placesi while he kept his telescope steadily fixed to one point, ^^ there passed over his field of vision, in the space of one quarter of an hour, no less than one hundred and aia^teen thotiaand stars, and at another time in forty-one minutes, no less than two hundred amlfifty-eight thousand?^ In all parts of the Milky-Way he found the stars unequally dispersea, and appearing to arrange themselves into separate clusters, in the small space, for example, between Beta and Sad'r, in Cygni, the stars seem to be clustering in two di- visions ; each division containing upwards of one hundred and sixtv-five thousand stars. At other observations, when examining a section of the Milky-Way, not apparently more than a yard in breadth, and six in length, he discoverea^/ify thousand stars, large enough to be distinctly counted ; and he suspected twice as many more, Avhich, for want of sufficient light in his telescope, he saw only now and then. It appears from numerous observations, that various changes are taking place amon^ the nebulae — that several nebulae are formed by the dissolution of larger ones, and that many ne- bulae of this kind are at present detaching themselves from the Milky- Way. In that part of it which is in the body of Scorpio, there is a large opening, about 4° broad, almost destitute of stars. These changes seem to indicate that mighty movements and vast operations are continually going on in the distant regions of the universe, upon a scale of mag- nitude and grandeur which baffles the human understanding. More than two thousand five hundred nebulae have already been observed ; and, if each of them contains as many stairs as the Milky -Way, several hundreds of millions of stars must exist, even within that portion of the heavens which lies open to our observation. *<0 whata confluence of ethereal fireS) From urns unnumber'd down the steep of heaven Streams to a point, and centres on my sight" Although the Milky- Way is more or less visible at all seasons of the year, yet it is seen to the best advantage du- ring the months of July, August, September, and October. When Lyra is on, or- near the mendian, it may be seen H It« throne of Juicier. Thu^ Ovid, tnh'" " "' And monalfi, by the name orMtlky, knnw ; NUtDn ailodes lo tbi^ in the £I>owuie lines :— **A broad and ample roac^ whoso duel is fold, And p*T«msnL stsrs, ai Mars lo thcc sppeai', B«ei>^ lbs oSaiy, that Milky- Wty, Which nlihUr, as a drcling zme, Ihou seeU Poodend wlui Han." runest uook i- ■-—* CHAPTER XV. IRiaiN or THE COHSTELLATIONB. OONSTBLLATIONa. 14 1 sons of Seth employed themselves in the study of astronomy , and that they wrote their obdervations upon two pillars, one of brick, and the other of stone,'" in order to preserve them against the destruction which Adam had foretold should come upon the earth. He also relates, that Abraham argued the unity and power of Grod, from the orderly course of thin^ both at sea and land, in their times and seasons, and from his observations upon the motions and influences of the smL moon, and stars ; and that he read lectures in astronomy and arithmetic to the Egyptians, of which they understood noth* ing till Abraham brought these sciences from Chaldea to Egypt ; from whence they passed to the Greeks. !Berosus also observes that Abraham was a great and just man, and famous for his celestial observations ; the mnkiny of which was thought to be so necessary to the human wef fare, that he assigns it as the principal reason of the Al- mighty's prolonging the life of man. This ancient historian tells us, in his account of the longevity of the antediluvians, that Providence found it necessary to prolong man's days, in order to promote the study and advancement of virtue, and the improvement of geometry and astronomy, which required, at least, six hundred years for making and perfectmg obser- vations.! When Alexander took Babylon, Calisthenes found that the most ancient observations existing on record in that city, were made by the Chaldeans about 1903 years before that period, which carries us back to the time of the dispersion of mankind by the confusion of tongues. It was 1500 years after this that the Babylonians sent to Hezekiah, to inquire about the shadow's going back on the dial of Ahaz. It is therefore very probable that the Chaldeans and Egyp- >ians were the original inventors of astronomy ; but at wnat period of the world they marked out the heavens into constel- lations, remains in uncertainty. La Place fixes the date thirteen or fourteen hundred years before the Christian era, sinc^ it was about this period, that Eudoxus constructed the first celestial sphere upon which the constellations were de- * Josephus alflrms, that " he saw himself that of stone to remain in Syria in his own tiudt" * Vince's Complete System of Astronomy, Vol. il. p. S44. ^— I ■ ■ ■ ■ ^ ^-- ■Ill I ■■-■■■■ — I ■■■_. ■■»■ — ■^^ — ■■ „ ■■ m, m MM^.^— ^^ What does Josephus relate concerning Abraham's knowledge of astronomy 9 Who. does he say, first Introduced this science Into Egypt) What other historian of remote antiquity etpeaks of Abraham's attention to this science? What reason does Beroras assign for the longevity of the antediluvians} When Alexander took Babylon, what anctent ohservaUons did he Und in that city? To what period of the world do theto observations canty us back? How long after this was it that the DabyloniMjS sent to Hezekiah, to inquire about the shadow's going back on the dial of Ahaz J ,^bunts of the constellations, of a higher antiquity than that event? Do any oT Uie ancient constenations refer to transacUons of a later date? What have tlie most Manned anUquarians of Europe done upon this subject, and of what do they assure US'* S^Jf?P would the memory of an action, or event, thus registered, be likely tit J^uxe? In arrrmglng the conslellaUons of the Zodiac, how was U natural to represent CONSTELLATIONS. 149 AVnen the sttn enters the sign Cancer, at the summer sol- t ce, he discontinues his progress towaras the north pole, and i e ins to return towards the south pole. This retrograde mo- t'( n was fitly represented by a Crab, which is said to go back- wards. The sun enters this sign aoout the 22d of June. The heat which usually follows in the next month, was represented by the Lion ; an animal remarkable for its herce- ness, and which at this season was frequently impelled by thirst, to leave the sandy desert, and make its appearance on the banks of the Nile. The sun entered the sixth sign about the time of harvest, which season Avas therefore represented by a Virgin, or female reaper, with an ear of com in her hand. At the autumnal equinox, when the sun enters Libra, the days and nights are equal all over the world, and seem to ob- seyye an equilibrium or balance. The sign was therefore represented under the symbol of a pair of Scales. Autumn, which produces fruit in gieat abundance, brings with it a variety of diseases^ and on this account was repre- sented by that venomous animal the Scorpion, which, as he recedes, wounds with a sting in his tail. The fall of tne leaf was the season for hunting, and the stars which mark the sun's path at this time were represented by a huntsman, or archer, with his arrows and weapons of destruction. The Goat, which delights in climbing and ascending some mountain or precipice, is the emblem of the winter solstice, when the sun begins to ascend from the southern tropic, and gradually to increase in height for the ensuing half year. Aquarius, or the Water-Bearer, is represented by the figure of a man pouring out water from an urn, an emblem of the dreary and uncomfortable season of winter. The last of the zodiacal constellations was Pisces^ or a couple of fishes, tied back to back, representing the nshing season. The severity of winter is over; the flocks do not afford sustenance, but the seas and rivers are open and pibound with fish. "Thus monstrous formSi o'er heaven's noctunal arch Seen hr the sage, in pomp celestial march ; See Aries there his glittering bow unfold, And raginc Taurus toss his horns of ffold; With bended bow the ^lullen Archer lowers, And there Aquarius comes with all his showers ; What sign was represented under the figure of a Cxab, and irhy) When does lb* •:un enterlhls sign 7 What animal represented the heat of sntnoer, and why f When, does the sun enter the sixth sign, and how is this season represeK*ed7 Why was ttift slfm which the sun enters at the autumnal equinox represented vmutt t he syn^ jof a Balance J Why were the autumnal signs, Scorpio and ^gltterius, reuitJMima^ they are? What does the Goat represent? What is signified by the yk w-B^ftrfl What do the Fishes represent? 13* 150 ORIGIN or THF Lions and Centaars, Gorgons. Hydras rise, And gods and heroes blaze along the skies."* Whatever may have led lo the adoj)tion of these rude names at first, they are now retained to avoid confusion. The early Greeks, however, displaced many of the Chal- dean constellations, and substituted such images in their place as had a more special reference to their own history. The Romans, also, pursued the same course with regard to their history; and nence the contradictory accounts that have. de- scended to later times. Some, moreover, with a desire to divest the science of the stars of its pagan jargon and profanity, have been induced to alter both the names and fibres of the constellations. In doing this, they have committed the opposite fault ; that of blending them with things sacred. The " venerable Bede," for example, instead of the profane names and figures of the twelve constellations of the Zodiac, substituted those of the twelve apostles, Junius Schillerius, following his example, completed the reformation in 1627, by giving Scripture names to all the constellations in the heavens. Weigelius, foo, a celebrated professor of mathematics in the university of Jena, made a new order of constellations, by converting the firma- ment into a cvhat proportion may this vast assemblage of suns and worlds bear to what lies beyond the utmost boundaries of human vision? How should we lenm from this to rcpard our own cartlu What does the immense distance -of the stars fTiw^ in regjinJ lolh^ir iuu;piltuJe ami li^rh'.? 154 MUMBEB, DISTANCE, AND revolve around it as a centre, and derive from it light and heat, and the agreeable vicissitudes of day and night. .^^ Tnese vast globes of light, then^ could never have been de- signed merely to diversify tne voids of infinite space, nor to shed a few glimmering rays on our far distant world, for th^ amusement of a few astronomers, who, but for the most pow- erful telescopes, had never seen the ten thousandth part of them. We may therefore rationally conclude, that wherever the All-wise Creator has exerted his creative power, there also he has placed intelligent beings to adore his goodness. f Hipparchas, the father of astronomy, first made a catalogue of the fixed stars. It contained l(h£. The accuracy with wiiich the places of these were recorded, has conferred essential benefit upon the science, and has enabled us to solve many celestial phenomena and problems of chronology, which other* wise had been difficult. During the 18th century, upwards of 100,000 were catalogued by the Tarimiv astronomers of Europe, ana their position in the heavens determined with an exactness that seldom varied a second from the truth ; insomuch that it has been justly remarked, that '* there is scarcely a star to be seen in the heavens, whose place and situation is not better known than tliat of ou^t cities and towns upon the earth." Dut the stargazers of our times are not idle. Professor Bessell of Konigs- berg, observed in three years, it is asserted, between 30,000 and 40^000 stara^ comprehended within a zone of IhP on each side of the equator ; but even this great number is but a small portion of the whole number which lie within the limit of the zone which he examined. To procure a more complete survey, the academy of Berlin proposed that thia same zone should be parcelled out among twenty- four observers, and that each should confine himself to an hour of right ascension, and examine it in minute detail. This plan was adopted ; and the ISth liour was confided to Professor Inghiraml, of Florence, and examined with so much care, that the positions of 75 000 stars in it, have been determined. Pro- fessor M. Struve, of tne Dorpat university, has examined in person, 120,000 stars, of which 800 (double ones; were before unknown to science. The labours of Sir Wm. Herschel were chiefiy devoted to exploring ti^p sys- tems of nebulae and double stars that lie, for the most part, bcvondthe rcfach of ordinary telescopes. No fewer than ttea thouaand jCvt hundred ncbuliB were observed by this indefatigal>le astronomer, whose places have been computed from his observations, reduced to a common epoch, nnd arranged into a cata- logue in order of their right aBc>snsion^ by his sister Miss Caroline Hbrschel, a lady so iustly celebrated in Europe for her astronomical knowledge and dis- coveries, out whose name, strange aa it is, is seldom mentioned in this country. Be it remembered, nevertheless, for her fame, that she discovered two of tne satellites of the planet which jDears her brother's name, besides a multitude of comets. 1 The greatest possible ingenuity and pains have been taken by astronomers to determine, at least, the approximate dis- tance of the nearest fixed stars. If they have hitherto been unable to arrive at any satisfactory result, they have at least, established a limit beyond which the stars must necessarily be placed. If they have failed to calculate their true distain- ces from the earth, it is because they have not the requisite data. The solution of the problem, if they had the data, would not be mpre difficult than to compute the relative dis- What conclusion may be drawn from this feet as to their great design? What pains have astronomers taken to find the distance of the stars, and what result have they «ome tor For what reason have they tailed to calculate their distance ? Is the pnii>- lem a difficult one? fiCONOMT OP THK STARS. ]55 fauces of the planets^^a thing which any sohool-boy can do. In estimating" so great a distance as the nearest fixed star, it 13 necessary that we employ the longest measure which astronomy can use. Accordingly, we take the whole diame- ter of the earth's orbit, which, in round numbers, is 190 millions of miles, and endeavour, by a simple process in mathematics, to ascertain how many measures of this length are contained in the mighty interval which separates us from the stars. The method of doin^ this can be explained to the appre- hension of the pupil, if he does not shnnk from the illustra- tion, through an idle fear that it is beyond his capacity. For example ; suppose that, with an instrument construct- ed for the purpose, we should this night take the precise bear- ing or angular directicm from us of some star in the northern hemisphere, and note it down with the most perfect exact- ness, and, having waited just six months, when the earth ^all have arrived at the opposite point of its orbit, 190 mill- ions of miles east of the place which we now occupy, we should then repeat our observation upon the same star, and see how much it had changed its position by our travelling so great a distance one side of it. Now it is evident, that u it changes its apparent position at all, the quantity of the change will bear som§ proportion to the distance gone over ; that is, the nearer the star, the greater the angle ; and the more remote the star, the less the angle. It is to be observed, ihat the angle thus found, is called the star's Anntuil Par- cdlax. But it is found by the most eminent astronomers of the ^ge, and the most perfect instruments ever made, that thia parallax does not exceed the four thousandth part of a de- gree, or a single second ; so that, if the whole great orbit of the earth were lighted up into a globe of fire 600 millions of miles in circumference, it would be seen from the nearest star only as a twinkling atom ; and to an observer placed at this distance, our sun, with its whole retinue of planetary worlds, would occupy a space scarcely exceeding tne thickness of a spider's web.* If the nearest of the fixed stars are placed at * A just Idea of the import of this term, will impaot a force and sublimity to an ez- pves«l appear to us to be fonit times as lai|;e as tbe sim, and give fouf times as mtich light and beat It is by no means unreasonable to sappose, that many of the fixed stars exceed a million of miles in diameter. We may pretty safely affirm, then^ that stars of the sixth magnitude, are not less than 900 millions of millions of miles distant from us $ or a million of times farther from us than the flanet Saturn, which is^ scarcely risible to the naked eye« (ut the human mind, in its present state, can no more appre- cia>te such distances than it can infinity ; for if our earth, which moves at more than the inconceivable velocity of a mill' ion and a half of miles a day, were to be hurried from its orbit, and to take the same rapid flight over this immense tract, it would not traverse it in sixteen hundred thousand years; and every ray of light, although it moves at the rate of one hundred and ninety>three thousand miles in a single second of time, is more than one hundred and seventy years in com- ing from the star to us. But what is even this, compared with that measureless ex- tent which the discoveries of the telescope indicate ? Ac- cording to Dr. Herschel, the light of some of the nebulae, just perceptible through his 40 feet telescope, must have been a million of ages in coming to the earth ; and should an)r of them be now destroyed, they would continue to be perceptible for a million of ages to come. Br. Herschel informs qs, that the glass which he nsed, would separate stara at 497 times the distance of Birius. ,' It is one of the wonders of creation that any phenomena of bodies at such an immense distance from us should be perceptible by human sight ; but it is a part of the Divine Maker's plan, that although they do not act physically upon OS, yet they should so rar be objects of our perception, as Suppose the light of Sirius to be twenty thousand million times less than tftat of •our Sun, how would it compare with that of a star of the sixth magnitude? V wa ■sttppose the two stars to be of the same slse, how much fertiter oft Is the star vt the sixth mas:nltude, than Sirius is ? Suppose Sirius to he placed where our Sun it, how t90Uld it» apparent magnitude, and Ue light end heat compare vHth those of the nm t What may we generally ailiim of the distance of stars of the sixth magnjftuder Can Se homan mind appreciate such distances? What ilhistratJioas can yovt give to show eir Immensity Jwliat is this distance compared with that of the telescopic stars* ' ihe neimlaet Why are we able to see bodies at so great a distance t t6S NDMBCR, DUrTAMCfi, AMD to expand our ideas of the vastness of the universe, and of the stupendous extent and operations of his omnipotence. " With these facts hcfore us," says an eminent astronomer and divine^ " it is most reasonable to conclude, that those ex- pressions m the Mosaic history of Creation, which relates to* the creation of the fixed stars, are not to be understood as referring? to the iime when they were brought into existence, as if they had been created about the same time with our eartli ; but as simply declaring the fact, that, at whatever pe* riod in duration they were created, they derived their exist" encefrom God,^^ ^ ^ • " That the stars here mentioned," ( Gen. i. 16.) says a dis- tinguished commentator,* " were the planets of our system, and not the fixed stars, seems a just mference from the fact, that after mentioning them, Moses immediately subjoins, ^ And Elohim set them in the firmament of the heaven to give light upon the earth, and to rule over the day and oyer the night j' evidently alluding to Venus and Jupiter, which are alternately our morning and evening stars, and which * ffive light upon vhe earth,' far surpassing in brilliancy any of the fixed stars." However vast the universte now appears; huWBver titlmcrDUs the vrorldt which may exist within its boundless rang;e, the lanvoage of Scripture^ and Scripture alone, is sufficiently comprehensive and suDlime, to express alt thtt emotions which naturally arise in the mind^ when contemplating its BtiHttttfd* This shows not onlv th6 harmony Which subsists between the discoveries of the Revelation and the discoveries of Science, but also forms by itself; a strong presumptive evidence, that the records of the Bible are authentic and divine. We have hitherto described the stars as being immoveable and at rest ; but from a series of observations on double stars. Dr. Herschel found that a great many of them have changea their situations with regard to each other ; that some perform revolutions about others, at known and regular periods^ and that the motion of some is direct, while that of others is re- trograde ; and that many of them have dark spots upon theii surface, and turn on their axes, like the sun. \ A remarkable change appears to be ^adually taking place in the relative distances of the stars m>m each other in the constellation Hercules. The stars in this region appear to' be spreading farther and farther apart, while those in the' opposite point of the heavens seem to close nearer and nearer together in the same manner as when walking through a * S. T urner, P. 8. A, R. A. 8. L., 1892. " ' ^' ■■■■ - ■■■■■»«■»■■■ — ^^— — i— ^ I ■^i ■■ ■ II I ■■^^^^»1^^— . I» I ■ ™ 1 ■ — l^M^M^ With these facts before us, wliat may we reasonably conclude with regard to the expressions in the Mos^c history which relate to the crtation of the toed stars ? What is the opinion of Mr. Turner in regard to the stars here mentioned? To what JSil-® expressfon, "To rule over the day and over the night," supposed to alludet SrtJ^SiSSS^iSSe'i^lSSi^rn^'Af''^ ""*"• '^^^^ '«»arkabl. changM ECONOMY OP THC STARa. 159 tS'fest, the trees towards which we adrance. appear to be constantly separating, while the distance between those which we leare behind, is gradually contracting. From this appearance it is concluded, that the Sun, with all its retinue of planetary worlds, is moying through the re- gions of the universe, towards some distant centre, or around some wide circumference, at the rate of sixty or seventy thousand miles an hour ; and that it is therefore highly prob able, if not absolutely certain, that we shaU never occupy that portion of absolute 8]aace^ through which we are at this moment passing, during all the succeeding ages of eternity.* The author of the Chhistian Philosopher endeavours to convey some idea of the boundless extent of the universe, by the following sublime illustration : — ^ Suppose that one of the highest order of intelligences is endowed with a power of rapid motion superior to that of light, and with a corresponding degree of intellectual enei^ ; \&Lt he has been fl3ring without intermission, from one pro* vince of creation to another, for six thousand yearsp and will continue the same rapid course for a. thousand millions years lo come ; it is highly probable, if not absolutely certain, that, at the end of this vast tour, he would have aavanced no far- ther than the ^ suburbs of creation^' — ^and that all the magnifi- cent systems of material and intellectual beings he had sur- veyed, during his rai>id flight, and for such a length of ages. Dear no more proportion to the whole empijre of Omnipotence than the smallest grain of sand does to all the particles or matter contained in ten thousand worlds." Were a seraph, in prosecuting the tour of creaticm in tha manner now stated, ever to arrive at a limit beyond which no farther displays of the Divinity could be perceived, the thought would overwhelm his faculties with unutterable emo* tionsj he would feel that he had now, in some measure, comprehended all the plans and operations of Omnipotence, and that no farther manifestation of the Divine glory remain- ed to be explored. But we may rest assured that this can never happen in the case of any created intelligence. There is moreover an axvument derivable finom the laws of the physical world^ that seems to stren^nen, I bad almost eaid, to confirm, this idea of the tnfimty of the material universe. It is this— jjT the number of etara bejinit9k and occupy only a part iif apace, the outward atara would be continually aMracted * Professor Bessel does not fall in with ttis ptevalMng opinion. What conclusion Is drawn trnta this appearance) SliaU we then pmhablyever occupy that portion of space through which we are now passing, again? What lllua» tnuion does the author of the Christian Philosopher give In order to convey sooaae idea of the boundless extent of the universe ? Were a seiaph ever to arrivo at a Itai^ beyond which no farther dlspliqrs of the divine glory could be perceived, how wouia ttM Vlea aflhct hbn? Is it probable that such a place exists in the universe, or wlthlm tho woa^ of any created intelllsence } 160 FALLIHO, OR BHOOtniG STARS. to those wtthmtimdin time wotddumtem one. But if the number he tv^htU^aatd they occupy an ir^nite epticey aU parte toould be nearly in equUibriOf and con- eequently each fixed etar^ being equally attracted in every directionf would keep its pUice. No wonder, then, that the Psalmist was so affected with the idea of the immensity of the universe, that he seems almost afraid lest he should be overlooked amidst the im- mensity of beings that must needs be under the superintend- ence or God ; or that any finite mortal should exclaiin, when contemplating the heavens — ^'^ What is man, that THOU art mindful of him i" CHAPTER XVII. FALUNO, OR SHOOTING STARS. ^ The phenomenon of shooting stars, as it is called, is com- mon to all parts of the earth ; but is most frequently seen in tropical regions. The unerring aim, the startling velocity, and vivid brightness with which they seem to dart athwart the sky, and as suddenly expire, excite our admiration; and we often ask, " What can they be?" But frequent as they are, this interesting phenomenon is not well understood. Some imagine that they are occasioned by electricity, and others, that they are nodiing but luminous gas. Others again have supposed, that some of them are luminous bodies which accompany the earth in its revolution around the sun, and that their return to certain places might be calculated with as much certainty and exactness as that of any of the comets. Dr. Burney, of Oosport, kept a record of all that he ob- served in the course of several years. The number which he noticed in 1819, was 121, and in 1820, he saw 131. Pro- fessor Green is confident that a much larger number are an- nually seen in the United States. Signior Baccaria supposed, they were occasioned by elec- tricity, and thinks this opinion is confirmed by the following observations. About an hour after sunset, he and scnne friends, that were with him, observed a falling star, directing its course directly towards them, and apparently growing larger and larger, but just before it reached them it disap- Where does the phenomenon of fUline, «r thootlnir etairB occur? Wliat 2s there to oxclte our achnixution in thlsjibenomenon 7 Is this Interesting phenfflnenon well un> derstood? What are the (Meient opinions in legaid to tbemf How many shootins stars did Dr. Burney observe in the years 1819 and isaof to it probable that % much larger number is seen evezy year in the United States? What did Baccaria suppose they were occasioned by, and what obsenratlouB did he maju to strengthfeii hto cpinlon* FALLIHG, OR SBOOTINQ STARS. I64 peared. On vanishing, their faces, hands, and clothes, with uie earth, and all the neighbouring objects, became suddenly illuminated with a diffused and lambent light. It was attend- ed with no noise. During their surprise at this appearance, a servant informed them, that he had seen a light shine sud- denly in the garden, and especially upon the streams which he was throwing to water it. The Signior also observed a quantity of electric matter col- lect about his kite, which had very much the appearance of a falling star. Sometimes he saw a kind of halo accompanying the kite, as it changed its place, leaving some glimmering of light in the place it had quitted. Shooting stars have been supposed by those meteorolopsts who refer them to electricity or luminous ^as, to prognosticate changes in the weather, such as rain, wind, &c. ; and there is, perhaps, some truth in this opinion. The duration of the brilliant tract which they leave behind them, in their motion through the air, will probably be found to be longer or shorter^ according as watery vapour abounds in the atmosphere. The notion that this phenomenon betokens hi^h winds^ is of great antiquity. Virgil, in the first book of his Georgics^ expresses the same idea : — <' Seepe eLiam Stellas vento impendente videbis PraBcipites ccelo labi ; noctisqae per mnbram Flainmarum longos a tergo albescere tractus. And otlf before tempestaous winds arise, The seeming stars tell headlong from the skies, And shooting through the darkness, gild the night With sweeping glories and long trails of light" The number of shooting stars, observed in a single night, though variable, is commonly very small. There are, how- ever, several instances on record of their falling in " showers" — ^wnen every star in the firmament seems loosened from its sphere, and moving m lawless flight from one end of the heavens to the other. As early as the year 473, in the montL of November, a phenomenon of this land took place near Constantinople. As Theophanes relates. '^ The sky appeared to be on fire," with the corruscations of tne flying meteors. A shower of stars, exactly similar took place in Canada, between the 3d and 4th of July, 1814 and another at Montreal, m November, 1819. In all these cases, a residaum, or black dttet^ was deposited upon the surface of the waters, and upon the roofs of buildings, and other objects. In the year 1810^ '* inflamed sub- stances,'* it is said, fell into and arouna lake Van, in Armenia, which stained the water of a blood colour, and cleft the earth in various places. Chi the 6th of What vras the appearance upon streams of waterf What did he observe at this time about his kite? What connexion are they supposed to have with meteorology i What oiTOunstanee may we probably find to confirm this idea? Is this notion of very ancient, or of modem date) What is, usually, the number of shooting stars observeil in a single night? When, and where, occurred the first Instance, ofl record, of their foiling m great numbers? Mention some other histances. What remarkable vutiga was Sm dy thtse meteoric showers ? U* 162 PALLING, OR SHOOTIRG STABS." September, 1819, « like phenomeaon was seen in Moravia. History fiimiehea many more instances of meteoric showers, depositing a rea du»t, in some places, ao plentiful as to admit of chymical analysts. The commissioner, (Mr. Andrew EUicott,) who was sent out by our gov^emment lo fix the boundary between the Spanish possessions in North America and the United States, witness- ed a very extraordinary flight of shooting stars, which filled the whole atmosphere from Cape Florida to the West India Islands. This grand phenomenon took place the 12th of November, 1799, and is thus described : — " I was called up," says Mr. Ellicolt, "about 3 o'clock in the morning, to see the shooting stars, as they are called. The phenomenon was grand and awiul. The whole heavens appeared as if illu- minated with skyrockets, which disappeared only by the light of the sun, after daybreak. The meteors, which at any one instant of time, appeared as numerous as the stars, flew ia all possible directions except^om the earth, towards which they all inclined more or less, and some ot them descended perpendicularly over the vessel we were in, so that I was in constant expectation of their falling on us." Mr. Eilicott further states that his thermometer which had been at 80 ° Fahr. for the four days preceding, fell to 56 ^ about 4 o'clock, A. M., and that nearly at the same time, the wind changed from the south to the northwest, from whence it blew with great violence for three days without intermission. These same appearances were observed, the same night, at Santa Fe de Bogota, Cumana, Gtuito, and Peru, in South America ; and as far north as Labrador and Greenland, ex- tending to Weimar in Germany, being thus visible over an extent on the globe of 64 ^ of latitude, and 94 ^ of longitude. The celebrated Humboldt, accompanied by M. Bompland, t)«en in S. America, thus speaks of the phenomenon: — '^Towards the morning of the I3th of No- vember, 1799, we witnessed a most extraordinary scene of shooting meteors. Thousands of bolides, and falling stars succeeded each other during four hours. Their direction was very regular from north to south. From the oeginning of the phenomenon there wae riot a space in the firui^ament, equal in extent to three diameters of the moon, which was not filled, every instant, with bolidea or falling stars. All the meteors left luminous traces, or pnc behind mem, which lasted seven or eight seconds." This phenomenon was witnessed by the Capuchin missionary at San Fer* fiando de Afiura, a village situat&d in lat. 7° 63 ' 12^^ amidst the savanoahs of the province of Vsurioas ; by the Franciscan monks stationed near the cataracts of the Oronoco, and at Marca, on the banks of the Rio Negro, j[«t 2^ 40' long. 70 <^ 21', and in the west of Brazil, as far as the equator itseif; and also at Uie city of Porto Cabello, lat. 10 ^ 6' 62", in French Guiana, Popayan, .^ . I . I . .Il l I mm^—^mmm^m^mm Recite instances of a similar ktnd, in which a red dust b#a been deposited. Describe tlie phenomenon of shooting stars described by Mr. ElUeott, in 1799. Describe ti»» tame phenomenon as seen, in Sottth America, by Humboldt. and others. In what or 40^ in r few seconds. On more attentive inspection it was seen, that the meteors exhibited three distinct varieties ; the Jirsty consisting of phosphofic lines, apparently described by a point ; the second, of large fireballs^ that at intervals darted along the sky, leav- ing luminous trains, which occasionally remained in view for a uimiber of minutes, and, in some cases, for half an hour or more ; the third, of undefined luminous bodies, which remain- ed nearly stationary in the heavens for a long time. Those of the first variety were the most numerous, and resembled a shower of fiery snow driven withinconceivable velocity to the north of west. The second kind appeared more \ik!^ falling stars — a spectacle which was contemplated by the more unenlightened beholders with great amazement andterrour. The trains which they left, were commonly white, but sometimes were tinged with various prismatic colours, of great beauty. These fireballs were occasionally of enormous size. Dr. Smith, of North Carolina, describes one which appeared larg- er than the full moon rising.* " I was," says he, " startled by the splendid light in which the surrounding scene was exhibited, renderino^ even small objects quite visible." The same ball, or a similar one, seen at New Haven, passed off in a northwest direction, and exploded a little northward of the star Capella, leaving, just behind the place of explosion, a train oi peculiar beauty. The line of direction was at first nearly straight ; but it soon began to contract in length, to dilate in breadth, and to assume the figure of a serpent scrol- ling itself up, until it appeared like a luminous cloud of va- pour, floating gracefully m the air, where it remained m full view for several minutes. Of the third variety of meteors, the following are remark- able examples : — At Foland, Ohio, a luminous body was dis- tinctly visible in the northeast for more than an hour. It was very orilliant, in the form of a pruning-hook, and apparently twenty feet long, and eighteen inches broad. It gradually * If this txxly were attiie distance of no miles, from the observer, it must have had a diameter of one mile ; if at the distance of 11 miles, its diameter was 68B feet ; and If only one mile off, it must have been 18 fleet in diameter. These considerations leave no doubt, tbad many of the meteors wese bodies of Uurge tUx. "Vfhai other appearances were (Observed, upon more attentive Inspection? GIv« a moie particular account of the first variety. Of the second. What do we know in regard to the size of these fireballs? How does Dr. Smith describe one seen by him in North Carolina? What was the anpearance of the same or a similar ball, as seen at New Haveni What was there peculiar in the course, and final disappearance of IC? SupjM^e thtd meteor toas no milu distant firom the place ef ohservoHon, what »tt«4 have been its dUmieter 7 What, If U were li mU^ distant J What, if anly one ttil^ } Mention some exxoaplea of the third vacie^ of meteon FALLIMO,\0R SHOOTING STARS. 165 settled towards toe honzon. until it disappeared. At Niagara Falls, a large, luminous body, shaped like a sqaare table^ was seen near the zenith, remaining for some time almost stationary, emitting lar^e streams of light. The point from which the meteors seemed to emanate, was observed by those who fixed its position among the stars, to be in the constellation Leo ; and, according to their concur- rent testimony, this radiant point was stationary amon^ the stars, during tne whole period of observation ; that is, it did not move fuong with the earth, in its diurnal revolution east- ward, but accompanied the stars in their apparent progress westward. A remarkable change of weather from warm to cold, ac- companied the meteoric shower, gs immediately followed it. In ail parts of the United States, this change was remarkable for its suddenness and intensity. In many places, the day preceding had been unusually warm for the season, but, be- tore the next morning, a severe frost ensued, unparalleled, for the time of year. In attempting to explain these mysterious phenomena, it is argued^ in the first place, that the meteors had their origin beyond the limits of our atmosphere ; that they of course did not belong to this earth, but to the regions of space exte- rior to it. The reason on which this concluskm is founded is this r— All bodies near the earth, including the atmoBphere itself have a common motion with the earth around its axis from west to east ; but the radiant point, that indicated the source from which the meteors emanated, followed the course of the stars from east to west; therefore, it was indeiMsndent of the earth's rotation, and consequently, at a great distance from it, and beyond the limits of the atmos- phere. Tlie height of the meteoric cloud, or radiant point, above the earth's surface -was,accor^nEto the mean average of Prc^essor (Nmsted's observa- tions, not less than 2Z& miles. That the meteors were constituted of very light, combus- tible materials, seems to be evident, from their exhibiting the actual phenomena of combustion, they being consumed, or converted into smoke, with intense light; and the extreme tenuity of the substance composing them is inferred from the fact that they were stopped by the resistance of the air. Had their quantity of matter been considerable, with so prodigious a velocity, they would. have had sufficient momentum to dash them upon the earth ; where the most disastrous consequences might have followed. bi what constellation was the point from which the meteors seemed to radiate? What changes wejo observed In the weather during or soon after this phenomenon? In attempting to account for these phenomena, what hypothesis has been advanced In rMfani to the place where the meteors bad tbelr oxlgin? What i» the reasonbtg: by which thUhypotheHa it nutained? How high wum me meteoric cloud aeuppoted to be above the earth 1 What do we know in regaxd to the substance of which the meteors i^ere composed ? What might have been the conseqioeiioes* if thetr T^umtity of matler Md been considezahle? 166 FALLING, OR SHOOTING STARS. Tlie momentum of even light bodies of such size, and in such nnmbers, tnv crsing the atmosphere with such astonishing Telocity, must have produced ex* tensive derausements in the atmospheric equilibrium. Cold air from the upper regions would be brought down to the earth ; the portions of air incumoent over districts of country remote from each other, being mutually displaced, would exchange places, the air of the warm latitudes be transferred to coldei, snd that of cold Is^itudes, to warmer regions. Various hypotheses have been proposed to account for this wonderful phenomena. The a^ent which most readOy suggests itself in this, and in many other unexplained natural appear- ances, is electricity. But no known properties of electricity are adequate to account for the production of the meteors, for the motions, or for the trains which they, in many instances, left behind them. Others, again, have referred their proximate cause to magnetism^ and to pnosphoretted hydrogen ; both of which, however, seem to be utterly insumcient, so far as their properties are known, to account for so unusual a phe- nomenon. Professor Olmsted, of Yale College^ who has taken much pains to collect facts, and to establish a permanent theory for the periodical recurrence of such phenomena, came to the conclusion, that — The meteors of November \Zth^ 1833, emanated from a nebuloits body, which was then pursuing its way along with the earth around the sun ; that this body continues to re- volve around the sun^ in an elliptical orbit — but little in- dined to the plane of the ecliptic^ and having its aphelion near the orbit of the earth; and finally^ that the body has a period of nearly six months, and thcU its perihelion is a little below the orbit of Mercury, This theory, at least accommodates itself to the remarkable fact, that almost all the phenomena of this description, which are known to have happened, have occurred in the two opposite months of April and November. A similar exhibition of meteors to that of November, 1833, was observed on the same day of the week, April 20th, 1803, at Richmond, in Virginia, Stockbridge, Massachusetts, and at Halifax, in British Amer- ica. Another was witnessed in the autumn of 1818, in the North sea, when, in the language of ,the observers, "all the surrounding atmosphere was enveloped in one expansive sea of fire, exhibiting the appearance of another Moscow ip flames." Exactly one year previous to the great phenomenon of 1833, namely, on the 12th of November, 1832, a similar me- What ^ect must the momentum tffeven light bodiet of aueh Hze,moving' loith «tMA velocUj/fhave had upon the atmosphere? Mention some hypotheses which have been proposed to account for these meteors. To what condusfon did Professor Olmsted, after a long hiveaUgaUon, come, in regard to them? TO what remarkable fistots In such phenomena, is this theory adapted ? At what other correspoodins periods havo «inular phenomena been observed ? FalunOj or shooting starb. 167 teoric display was seen near Alocha, on the Red 8eIantations, amount- ing in all to aliout six or eight hundred. Wliile earnestly listening for tho cause, I heard a faint voice near the door calling my name ; 1 arose, and taking my sword, stood at the door. At this moment, I heard the same roice still beseeching me to rise, and saying, 'O! my God, the world is on fire!' I then opened the door, and it is difficult to nay whirh excited me moat — the awfulness of the scene, or the distressed cries of the negroes ; upwards of one hundred lay prostrate on the ground— some speechless, and some with the bitterest cries, but most with their hands raised, imploring Clod to aare the world and them. The scene was truly awful ; for never did run foil much thicker, than the meteors fell towards the earth ; east, west, north, and aoiilh» it was the same I*' Since the 'preceding went tg pressj the Author has been po- litely furnished, by Professor Ohnsted, with the accom" panying communication, " I am happy to hear that you propose to stereotype your ' Geography of the Heavens.' It has done much, I believe, to diffuse a popular knowledge of astronomy, and I am pleased that your efforts are rewarded by an ex- tended patronage. "Were I now to express my views on the subject {Me- teoric Showers) in as condensed a form as possible, I should state them in some such terms as the following : The mete- oric showers which have occurred for several years past on or about the 13th of November, are characterized by four peculiarities, which distinguished them from ordinary shooting stars. First, they are far more numerous than common, and are larger and brighter. Secondly, they are in much greater proportion than usual, accompanied by luminous trains. Thirdly, they mostly appear to radiate from a common centre, — that is, were their paths in the heavens traced backwards, they would meet in the same part of the heavens : this point has for three years past, at least, been situated in the constellation Leo. Fourthly, the greatest display is every where at .nearly the same time of night, namely, from three to four o'clock — a time 16d FALLtltii, OR dbboHKd S^AttS. about half way ft^m midnight to sunrise. Th^ tneltiOf B are inferred to 2»« ^hieh now romain to be considered, litoated? Which of them ere the moat importaiH? 15 170 Q£NSRAL PHENOMENA markable not only for changes of position ', but fur the varied phases or appearances which she presents, as she waxes from her crescent form through all her diffeient stages of increase to a full orb, and wanes back again to her former diminished figure. The partial or total obscuration of these two bodies, which sometimes occurs, darkness taking place even at mid-day, and the face of night, before lighted up by the Moon's beams, being suddenly shaded by their absence, have always been among the most striking astronomical phenomena, and. so powerful in their influence upon the beholders, as to fill them with perplexity and fear. If we observe these two bodies, we shall find, that, besides their apparent diurnal motion across the heavens, they exhibit other phenomena, which must be the effect of motion. The Sun during one part of the year, will be seen to rise every day farther and farther towards the north, to continue longer and longer above the horizon, to be more and more elevated at mid-day, until he«rrives at a certain limit; and then, during the other part, the order is entirely reversed. The Moon sometimes is not seen at all ; and then, when she first becomes visible, appears in the west, not far from the setting Sun, with a slen- der crescent form; every night she appears at a greater distance from the setting Sun, increasing in size, until at length she is found in the east, just as the Sun is sinking below the horizon in the west. The Sun, if his motions be attentively^ observed, will be found to have another motion, opposite to his apparent diurnal motion from east to west. This may be perceived distinct- ly, if we notice, on any clear evening, any bright star, which is first visible after sunset, near the place where he sunk below the horizon. The following evening, the star will not be visible on account of the approach of the Sun, and all the stars on the east of it will be successively eclipsed by his rays, until he shall have made a complete apparent revo- lution in the heavens. These are the most obvious pheno- mena exhibited by these two bodies. There are, also, situated within the limits of the Zodiac, certain other bodies, which, a4 first view, and on a superficial examination, are scarcely distinguishable from the fixed stars. But observed more attentively, they will be seen to shine with a milder and steadier light, and besides being carried round with the stars, in the apparent revolution oF the great celestial concave, they will seem to change their Describe the most i^oua pheumiena of Uie Sun end Moon. 2>efcribe the meet obnow phenomena of the planets. OP TtlE SOLAR s7Enri:M. 171 [)isices la the concave itself. Sometimes they are station- ary ; sometimes they appear to be moving from west to east, and sometimes to oe going back again from east to west; being seen at sunset sometimes in the east, and sometimes* in the west, and always apparently changing their position with regard to the earth, each other, and the other heaven- ly bodies. From their wandering as it were, in this man- ner, through the heavens, they were called by the Greeks jrXtti/ijrai, plancts, which signifies wanderers. There also sometimes appear in the heavens, bodies of a very extraordinary aspect, which continue visible for a con- siderable period, and then disappear from our view; and noth- ing more is seen of them, it may be for years, when they again present themselves, and take their place among the bodies of the celestial sphere. They are distinguished from the planets by a dull and cloudy appearance, and by a train of light. As they approach the sun, however, their faint and nebulous light becomes more and more brilliant, and their train increases in length, until they arrive at their nearest point of approximation, when they shine with their greatest briJliancy. As they recede from the Sun, they gradually lose their splendour, resume their faint and nebulous appear- ance, and their train diminishes, until they entirely disap- pear. They have no well defined figure ; they seem to move in every possible direction, and are found in every part of the heavens. From their train, they were called by the Greeks Ko/iTjraj, comets, which signifies having long hair. The causes of these various phenomena must have early constituted a very natural subject of inquiry. Accordingly, we shall find, if we examine the history of the science, that in very early times there were many speculations upon this subject, and that difl^erent theories were adopted to ac- count for these celestial appearances. The Egyptians, Chaldeans, Indians, and Chinese, early possessed many astro* Domical facts, many observations of important phenomena, and many rules and methods of astronomical calculation; and it has been imagined, that they bad the ruins of a great system of astronomical science, which, in iho earliest a^res of the world, had been carried to a great degree of perfection, and that while the principles and explanations of the plienomena were lost the isolated, unconnected facta, rules of calculation, and phenomena themselves, remain- ed. Thus, the Chinese, who, it is generally agreed, possess the oldest authen- tic observations on record, nave recorded in their annals, a conjunction of five planets at the same time, which happened 2461 years before Cnrist. or 100 years before the flood. By mathematical calculation, it is ascertained that this conjunction really occurred at that time. The first observation of a solar eclipse of which the world has any knowledge, was made by the Chinese, 2128 years before Christ, or 220 years after the deluge. It seems, also, that the Chinese understood the method of calculating eclipses ; for, it is said, that the ^ ■■■ !■ ^— — ^-^.^— ■■ n il I ■■!■»■■■■ ■ — ■■■■■■■ — ■■.. ■■ ■ . ■ ■■■■^ Whence do tliey derive their name ? Describe the comets. "Whence is their name derived 7 What orien tal nations early possessed nany important aatronamical fact* obseroationst and rules ? Whence is it supposed that they obtained them ? X 172 OfiMERAL PHENOMENA emperor was so irritated against the great officers of state for neglecting to pre 'diet the eclipse, that he caused them to be put to death.* The astrrmomical epoch of t!ie Chinese, according to Bailly, commenced with Fot'i, their first emperor, who flourished 2952 years before the Christian era, or about 950 years before the delude. If it be asked how the knowledge of this antedilu- vian astronomy was preserved and transmitted, it is said that the columns ou which it was registered have survived the deluge, and that those of EgyjU are only copies which have become originals, now that the others hare been for* gotten. The Indians, also, profess to have many celestial observations of a very early date. The Chaldeans have been justly celebrated in all ages for their astronomical observations. When Alexander took Babylon, his precep- tor, Callisthenes, found a series of Chaldean observations, made in that city, and extending back with little interruption, through a period of 1903 vears pre- ceding that event. This would carry us back to at least 2234 years before the birth of Christ, or to about the time of the dispersion of mankind by the con- fusion of tongues. Though it be conceded, that upon this whole period in the history of the science, the obscurity of very remote antiquity must necessari- ly rest, still it will remain evident that the plienomena of the heavenly bodies had been observed with great attention, and had been a subject of no ordinary interest. fiut however numerous or important were the observations of oriental an- tiquity, they were never reduced to the shape and symmetry of a regular system. The Greeks, in all iirobability, derived many notions in regard to this sci- ence, and many facts atid observations, from Egypt, the great fountain if an- cient learning and wisdom, and many were the speculations and hypotheses of their philosophers. In the fabulous period of Grecian history. Atlas. Her* cules, Linus, and Orpheus, are mentioned as persons distinguished for their knowledge of astronomy, a!nd for the improvements which they made in the science. But in regard to this period, little is known with certainty, and it must be considered^ as it is termed, fabulous. The first of the Greek philosophers who taught Astrono- my, was Thales, of Miletus. He flourished ahout 640 years before the Christian era. Then followed Anaximan- der, Anaximenes, Anaxagoras, Pythagoras, Plato. — Sonje of the doctrines maintained by these philosophers were, that the Earth was round, that it had two motions, a diurnal mo- tion on its axis, and an annual motion around the Sun, that the Sun was a globe of fire, that the Moon received her light fro«n the Sun, that she was habitable, contained mountains^ seas, &c. ; that her eclipses were caused by the Earth's shadow, that the phmets were not designed merely to adorn cur heavens, that they were worlds of themselves, and thai the fixed stars were centres of distant systems. Some of them, however, maintained, that the Earth was flat, and others, that though round, it was at rest in the centre of the universe. When that distinguished school of philosophy was estab- lished at Alexandria, in Egypt, by the munificence of the * It is well kno^vn tliat the Chinese have, from time immemorial, considered Solar Cclipsea and Conjunctions of the planets, as wognosUcs of importance to the Empire, and that they have been predicted as a matter of State pa'icy. Give some instances. Were these facts, however, reduced to a science ? Whence, is it probable, that the Greeks derived their first notions of astronomy 1 What is the name of the first of the Greek pliilosophcrs vpho taught astronomy ? At what time did he liou>i«h? Wliat Greek philosophers otler him taught npca the same subject 1 Men- tk)n soiporn at Knudstorp, in Norway, in 1546. Saeh wa« tli« distinction which he had attained as an astronomer, that when dissatisfied with his residence in Denmark, he had re- solved to remove, the king of Denmark, learning his inten- tions, detained him in the. kingdom, by presenting him with the canonry of Rothschild, with an income of 2000 crowns per annum. He added to this sum a pension of 1000 crowns, gave him the island of Huen, and established for him an ob servatory at an expense of about 200,000 crowns. Here T^cho continued, for twenty-one years, to enrich astronomy with his observations. His observations upon the Moon were important, and upon the planets, numerous and precise, and have formed the data of the present generalizations in astronomy. He, however, rejected the system of Coperni- cus ; considering the Earth as immoveable in the centre oi the system, while the Sun, with all the planets and comets revolving around him, performed his revolution around the earth, and, in the course of twenty-four hours, the stars also revolved about the central body. This theory was not as simple as that of Coperojcus, and involved the absurdity of making the Sun, planets, &c, revolve around a body com- paratively insignificant. Near the close of the 15th century, arose two men, who WT0U£:ht most important changes in the science, Kepler, and Galileo, the former a German, the latter an Italian. Previous to Kepler, all investigations proceeded upon the supposition that the planets moved in circular orbits, which had been a source of much error. This supposition Kepler showed to be false. He discovered that their orbits were ellipses. The orbits of their secondaries or moons he also found to be the same curve. He next determined the di- mensions of the orbits of the planets, and found to what their velocities in their motions througn their orbits, and the times of their revolutions, were proportioned 5 all truths of the greatest importance to the science. While Kepler was making these discoveries of facts, very essential for the explanation of many phenomena, Galileo was discovering wonders in the heavens never before seen by the eye of man. Having improved the telescope, and applied it to the heavens, he observed mountains and valleys upon the surface of our Moon ; satellites or secondaries WhatiiiduoeinentadidthekincofDenmaarkoflkrhimtoiemaipiiiUie]^^ How lOQgdid he continae to make obsenrationB in hisobservatorrin tbe luiuaaof Huea7 Btow vrere the heavenly bodies arranged, in his ■ystem I What absunhty did it mwlw 7 WJiat two iUtutiiooB astronomen made several very important diacovenea soon «wr ««L2«t ofTychoBrahe? What were the discoveries of Kepler J What were the discovertes or Galileo? 176 GENERAL PHBlfOMElTA were discovered revolving about Jupiter; and Venus, as Copernicus had predicted, was seen exhibiting all the differ- ent phases of the Moon, waxing and waning as she doesj through various forms. Many^ minute stars, not visible to the naked eye, were descried in the milky-way ', and the largest fixed stars, instead of being magnified, appeared to be small brilliant points, an incontrovertible argument in fa- vour of their immense distance from us. All his discoveries served to confirm the Copernican theory, and to show the absurdity of the hypothesis of Ptolemy. Although the general arrangement and motions of the planetary bodies, together with the figure of their orbits, had been thus determined^ the force or power which car- ries them around in their orbits, was as yet unknown. The discovery of this was reserved for the illustrious New- ton.* By reflecting on the nature of gravity — that power which causes bodies to descend towards the centre of the earth— since it does not sensibly diminish at the greatest dis- tance from the centre of the earth to which we can attain, be- ing as powerful on the loftiest mountains as it is in the deep- est caverns, he was led to imagine that it might extend to the Moon, and that it might be the power which kept her in her orbit, and caused her to revolve around the Earth. He was next led to suppose that perhaps the same power carried the Erimary planets around the Sun. By a series of calculations, e was enabled at length to establish the fact, that the same force which determines the fall of an apple to the Earth, car- ries the moons in their orbits around the planets, and the planets and comets in their orbits around the Sun. To recapitulate briefly : the system, (not hypothesis, for much of it has been established bv mathematical demonstra- tion,^ by which we are now enabled to explain with a beauti- ful simplicity the different phenomena of the Sun, planets, moons, and comets, is, that the Sun is the central body ia the system ; that the planets and comets move round him in elliptical orbits, whose planes are more or less inclined to each other, witn velocities bearing to each otherf a cer- tain ascertained relation, and in times related to their dis- tances ; that the moons^ or secondaries, revolve in like man* ner, about their primanes, and at the same time accompany * The dsoovery of Newton wu in Mme meaaun anticipated by Ccipemeaa, Keplar and Hooke. t Theorbite or oaths of the planets were diseoveied by tzadnc tbe eomse of the phnet bjr reans of the fficed stats. ^^ ^^S^hy^J^ ^•■"'yW of Newton 7 How was he led to make it J Recapitutal^ tenfljr the system by which it^e aie enahkd to explaaa the diSerent celestial pt >^ OP THE SOLAR SYSTEM. 177 ^em ia their motion around the Sun ; all meanwhile reyol- Ting on axes of their own ; and that these revolutions in their orbits, are produced b^ the mysterious power of attraction. The particular mode m which this system is applied to the explanation of the different phenomena, will oe exhibitca as we proceed to consider, one by one, the several bodies above mentioned. These bodies, thus arranged and thus revolving, consti tute what is termed the solar system. The planets have , been divided into two classes, primaries and secondaries. The latter are also termed moons, and sometimes satellites. The primaries are those which revolve about the Sun, as a centre. The secondaries are those which revolve about the primaries. There have been discovered eleven prima- ries ; namely, Mercury, Venus, the Earth, Mars, Vesta, Juno, Ceres, Pallas, Jupiter, Saturn, and Herscbel ; of which, Mercury is the nearest to the Sun, and the others follow, in the order in which they are named. Vesta, Juno, Ceres, and Pallas, were discovered by means of the telescope, and, because they are very small, compared with the others, are called asteroids. There have been discovered, eighteen secondaries. Of these, the Earth has one, Jupiter four, Saturn seven, and Herschel six. All these, except our Moon, as well as the asteroids, are invisible to the naked eye. jr^ > . Plate 1, of the AtlsLS, " exhibits a plan of the Solar System," comprising tha relative magnitudes of the Sun and Planets ; their comparative distances from the. Sun, and from each other; the position of their orbits, with respect to each other, the Earth, and the Sun ; together with many other parUculars which are explained on the map. There, the first and most prominent object which claims attention, is the representation of the Sun's circumference, witli its deep radiations, bounding the upper margin of the map. It is apparent, however, that thia segment is hardly one sixth of the whole circumference of which it is a part. Were the man sufficiently large to admit the entire orb of the Sun, even upon so diminutive a scale as there represented, we should then see the Sun and Planets in their just proportions— the diameter of the former being 112 times the diameter of the Earth. It was intended, originally, to represent the Earth upon a scale of one inch In diameter, and the other bodies in that proportion ; but it was found that It would increase the map to 4 times its size ; and hence it became necessary to assume a scale of /m|/ an inch for the Earth's diameter, which makes that of the Sun 56 inches, and the other bodies, as represented upon the map. The relative position of the Planets* Orbits is also represented, on a scale as large as the sheet would permit. Their relative distances from the Sun as a centre, and from each other, are there shown correctly : But had we wished to enlarge the dimensions of these orbits, so that they would exactly corrcs- eond with the scale to which we have drawn the planets, the map must have ecn nearly 4 miles in length. Hence, says Sir John Herschel, "the idea that What ia meant by tlie Solar System ? Into what two classes have the planets been di • videtl? Define n primary planet. Define a secondary planet How ipany.immaty plan rts have been discovered ? What aie their names, and whiUt the order of their diiitanos from the sun ? Whi<* of Ihem were discovered by means of the te*^«»^' Y« »C! these termed asteroids ? How many seoondanes have been ofooj&^^J^ow "«»» diBtribnted among the primaries J Wluch of the pnmaries and secondaries am invisiftl* to the naked eye? 178 THE SUN. we can convey correct notions on this snbject, hj drawing circles on papef la out of the question." To illustrate this. — ^Let us suppose ourselves standing on an extended plan««, or field of ice, and that a globe 4 feet 8 inches in diameter is placed in the centre of the plane, to represent tlic Bun. Having cut out of the map, f ne dark circles representing the planets, we may proceed to arrange them in their respective orbits, about the Bun, as follows : first, we should take Mercury, about the size of a small currant, and place it on the circumference of a circle 194 feet from the dun ; this circle would represent the orbit of Mercury, in the proper ratio of its magnitude. Next, we should take Venus, about the size of a rather small cherry, and place it on a circle 362 feet from the Sun, to represent the orbit of Venus : Then would come the Earth, about the size of a cherry, revolving in an orbkSOO feet from the Sun : — After the Earth, we should place Mars, about the size of a cranber- ry, on a circle 762 feet from the Sun :— Neglecting the Asteroids, some of which would not be larger than a pin's head, we should place Jupiter, hardly equal to a moderate sized melon, on a circle at the distance of half a mile (2601 feet) from the Sun ;^Saturn, somewhat less, on a eirle nearly a mile (4769 feet) from the Sun ; and last of all, we should place Ilerschel, about the size of a 8 each, on the circumference of a circle nearly 2 miles (9591 feet) from the on. To imitate the motions of the planets, in the aboveroentioned orbits, Mercn* ry must describe its own diameter in 41 seconds ; Venus, in 4 minutes 14 seconds ; the Earth, in 7 minutes ; Mars, in 4 minutes 48 seconds ; Jupiter, In 2 hours 66 minutes ; Saturn, in 3 hours 13 minutes ; and Ilerschel, in 2 hours 16 minutes. Many other interesting subjects are embraced in Plate 1 ; but they are either explained on the m^>, or in the fr^llnwing Chapters, to which they res* pectively relate. CHAPTER XIX. THE StJN. The sun is a vast globe, in the centre of the solar system, dispensing light and beat to all the planets, and govern- ing all their motions* It is the great parent of vegetable life, giving warmth to the seasons, and colour to the landscape. Its rays are the cause of various vicissitudes on the surface of the earth and in the atmosphere. By their agency, all winds are pro- duced, and the waters of the sea are made to circulate in vapour through the air, and irrigate the land, producing springs and rivers. The Sun is by far the largest of the heavenly bodies whose dimensions have been ascertained. Its diameter is something more than 887 thousand miles. Consequently, it contains a volume of matter equal to fourteen hundred thou- sand globes of the size of the Earth. Of a body so vast in its'dimensions, the human mind, with all its efforts, can ^ ■ ^^^1^ ■ ■ ■ ■ I ■ ■»■ — I ■ P ^.^m^a^ ,m ■ ^i.^—— ^ » ■■■»■-■ - ™ Mention ■ome of the efiecta produced by the Sun. Wliat is its macmitiide compared with, that of the other heavenly bodiea whose dimensions have been estunated 1 What ft ta diameter I How much larger is the Sun than the Earth 7 THE BUM. 179 liprm no adequate conception. The whole distance between the Earth and the Moon would not suffice to embrace one third of its diameter. Here let the student re/er to "Plate I. where the Relative Magnitudes of tb« Sua and Planets are exhibited. Let him compare the segment of the Bon's circumference, ais there represented, with the entire circumference of the Barth. They are both drawn upon the same scale. The segment of the Sun's circumference, since it is almost a straight line, must be a very small part of what the whole circumference would be, were it represented entire. Let the student understand this diagram, and he will be in some measure able to con- ceive how like a mere point the Earth is, compared with the Sun, and to form in his mind some image of the vast magnitude of the latter. Were the Sun a hollow sphere, perforated with a thousand openings to admit the twinkling of the luminous atmosohere around it — and were a globe as large as the Earth placed at its centre, with a satellite as large as our Moon, and at the same distance from it as she is from the earth, there would be present to the eye of a spectator on the interior globe, a universe as splendid as that which now appears to theun- instructed eye — a universe as large and extensive as the whole creation was conceived to be, in the infancy of astron* onoy. The next thing which fills the mind with wonder, is the distance at which so great a body must be placed, to occupy, apparently, so small a space in the firmament. The Sun^s mean distance from the Earth, is twelve thousand times the Earth's diameter, or a little more than 95 millions of miles. We may derive some faint conception of such a distance, by considering that the swiftest steamboats, which ply our waters at the rate of 200 miles a day, would hot traverse it m thirteen hundred years ; and, that a cannon ball, flying night and day, at the rate of 16 miles a minute, would not reach it in eleven years. The Sun, when viewed through a telescope, presents th« appearance of an enormous globe of fire, frequently in a state of violent agitation or ebullition j dark spots of irregu- lar form, rarely visible to the naked eye, sometimes pass over his disc, from east to west, in the period of nearly fourteen days. These spots are usually surrounded by a penumbra, and that, by a margin of light, more brilliant than that of the Sun. A spot when first seen on the eastern edge of the Sun, appears like a line which progressively extends in breadth, till it reaches the middle, when it begins to contract, What ii the whole distance between the Earth and the Moon, compued v^tb the d^ ameter of the Sun? Give some iliiMtration to enable oa to coneeNe « *f|« »S«K£*toJ2f the Sun. What is the diatanneofthc Sun from the Earth? Q»w»o™f »^!^Sgg?^£ja able us to conceive of the distance What ts the appeatance of the fun vbenjwwea througfaa telescope? In what time do the spots seen on the Sun pass a««B w© a»of In what direction do they move? Deeeribe their appearance. v60 tHfi s0tr. and ultimately disappears, at the western ^^e. In some rare instances, the same spots re appear on tne east side, and are permanent for two or three rerolations. But, as a general thing, the spots on the Sun are^ neither permanent nor uniform. Sometimes several small ones unite into a large one ; and, again, a large one separates into numer- ous small ones. Some contiDue seveial days, weeks, and even months, together ; while others appear and disappear, in the course of a few hours. Those spots that are formea gradually, are, for the most part, as gradually dissolved ; whilst those that are suddenly formed, generally vanish as quickly. It is the general opinion, that spots on the Sun were first discovered by Galileo, in the beginning of the year 1611 ; though Scheiner, Harriot, and Fabricius, observed them about the same time. During a period of 18 years from this time, the Sun was never found entirely clear of spots, excepting a few days in December, 1624 ; at other times, there were frequently seen, twenty or thirty at a time, and in 1625, upwards of fifty were seen at once. Prom 1650, to 1670, scarcely any spots were to be seen ; and, from 1676, to 16S4, the orb of the Sun presented an un- spotted disc. Since the beginning of the eighteenth cen- tury, scarcely a year has passed, m which spots have not been visible, and frequently in great numbers. In 1799, Dr. Herschel observed one nearly 30,000 miles in breadth. A single second of angular measure, on the Surf's disc, as seen from the earth, corresponds to 462 miles ; and a circle of this diameter (containing there* fore nearly 220,000 square miles) is the least space which can be distinctly dis* eerned on the 8un as a vinble area^ even by the most powerful glasses. tSpo'a have been observed^ however, whose linear diameter has been more than 44»000 miles; and, if some records are to be trusted, of even still greater extent Db. Dick, in a letter to the author, says, " I have for many years examined the solar spots with considerable minuteness, and have several times seen spots which were not less than the one twentyrfifth part of the Snn's diameter, which would make them about 22,^92 miles in diameter, yet they were visible neither to the naked eye, nor through an opera glass, magnifying about three times. And, therefore, if any spots have been visible to the naked eye — which we must believe, unless we refuse respectable testimony — they could not have been much less than 60,000 miles in diameter." The apparent motion of these spots over the Sun*s sur- face, is continually varying in its direction. Sometimes they seem to move across it in straight lines, at others in curoe lines. These phenomena may be familiarly illustra- ted in the following manner. Do the saffle nwts ever re;a|)|)ear m the east side } Are the spots generally penaanaH and uniform 7 Deseribe their nrenilanlws ) Who. is it saiemny sapposed. fint diacovw- Mngtaoo the Sun? Who ebe obaervod them about the same thne ? What was Om ireadth of the one seen by Dr. Henchcl m 17M } In what the influence of the solar rays, so as to produce that degree of aenaihle heut requisite to the wants, and to the greatest benefit of each of the planets. On this hypothesis, which is corroborated by a great variety of facts and experiments, there may be no more sensible heat experienced oa the planet Mercu^, than on the surface of Herschel, which is fifty times farther removed from the Sun. Owing to the dazzling brightness of Mercury, the swift- ness of its motion, and its nearness to the Sun, astronomers have made but comparatively few discoveries respecting It. When viewed through a telescope of considerable magnifying power, it exhioits at different periods, all the various phases of the Moon ; except that it never appears quite full, because its enlightened hemisphere is never turned directly towards the Earth, only when it is behind the Sun, or so near to it, as to be hidden by the splendour of its beam&\ Its enlightened hemisphere being thus always turn- ed towards the Sun, and the opposite one oeing always dark, prove that it is an opaque body, similar to the Earth, shining only in the light which it receives from the Sun. The rotation of Mercury on its axis, was determined from 'he daily position of its horns, by M. Schroeter, who not only discovered spots upon its surface, but several mountains in its southern hemisphere, one of which was 10^ miles high : — nearly three times as high as Chimborazo, in South America. It is worthy of observation, that the highest mountains which have been dia* covered in Mercury, Venus, the Moon, and perhaps we may add the Earth, are all situated in their southern hemispheres. During a few days in March and April, August and S^p« tember. Mercury may be seen for several minutes, in the morning or evening twilight, when its greatest elongations happen in those months ; in all other parts of its orbit, it is too near the Sun to be seen by the naked eye. The greatest On what does the degree of heat at the different planets probahitf depend 7 Why have Bstronomen been able to make but comparatively few discoveries respecting Mer- cury ? What is its appearance when viewed through a telescope of considerable nianii&^ nw power? What circumstances prove that it is an opaque body, shinins only with the UKht of the sUn J How was the rotation of Mercury on its axis determined, and by whom ? what did he discover on its surface? Wliat was the altitude of the hiKhesc mountain which he saw ? In which hemisphere are the Mgheat mountains tohich have been dieeovered in Mercury, Venus, and the Moon, situated 7 Does the same fact exist in regmrd to the EarthT Durins what months may Mercury be seen for a few days, ao* m what parts of the day 7 Why is it visible at these Umes. and not at othen I distance that it ever departs from the San, on either side, varies from 16° 12', to 28^ 48', alternately. The distance of a planet from the Sun, as seen from the Earth, (measared in degrees.) is called its ekingation. The greatest absolute distance of a planet from the Sun is denominated its aphelion^ and the least its perihelion. On the diagram, exhibiting tlie Relative Position of tiie Pianets' Orbits, [Plate I.] these fioints are represented by liitle dots in the orbits at the extremities of the right ines which meet them ; the Perilielion points being above the Ecliptic, the Aphelion points below it. The revolution of Mercury about the Sud, like that of all the planets^ is performed from west to east, in an orbit which is nearly circular. Its apparent motion as seen from the , earth, is, alternately, from west to east, and from east to west, nearly in straight lines ; sometimes, directly across the face of the Sud, but at all other times, either a little above, or a little below it. Being commonly immersed in (he Sun's rays in the evening, and thus continuing invisible till it emers^es from them in the morning, it appeared to the ancients like two distinct stars. A long series of observations was requisite, before they recognised the identity of the star which was seen to recede from the Sun in the morning with that which approached it in the evening. But as the one was never seen until the other disappeared, both were at last found to be the same planet, which thus oscillated on each side of the Sun. Mercury's oscillation from west to east, or from east to west, is really aceomplilhed in just half the time of its reyo- lution, which is about 44 days; but as the Earth, in the mean- time, follows the Sun in the same direction, the apparent elongations will be prolonged to between 55 and 65 davs. The passage of Mercury^ over the Sun's disc, is aeno- minated a Transit. This would happen in every revo- lution, if the orbit lay in the same plane with the orbit of the Earth. But it does not ; it cuts the Earth's orbit in two opposite points, as the ecliptic does the equator, but at an angle three times less. See diagram, Relative Position of the Planets' Orbits, and their Inclination to the Plane of the EU^liptic. [Plate I.] The dark lines denote sections in the planes of the planets' orbits. The dotted lines continued from the daric lines denote tlie inclination of the orbits to the plane of the Ecliptic, which inclina- tion is marlced in figures on them. Let the student fancy as many circular pieces of pag^r, intersecting each other at the several angles of inclination Wliat are tiie greatest distances which it departs from the Sun, on either side 7 WTut la the Elongation of a planet 7 What U its Aphelion 7 What ia ita Perihelion 7 In what direction does Mercury revolve about the Sun ] What is the figure of its orbit 7 De* scribe its apparent motion, as seen from the Earth. How did it appear to the ancients } Wliat was the cause of this appearance ? How were these apparently two diatitict stars at last found to be but one 7 what is the actual period of each elongation of Mecouqr) . What the apparent period? Wfaatis tbecauseofthisdi£&rence7. What does the ezproa* sioo, transit of Mercury, signify 7 Why docs it not make a transit at every rsvdutwnl 16* 186 BicacuitT. The foUowinff is a list of all the Transits of Mercury from was observed by Gassendi, November 6, 1631, to the end of tury. ' 1707 May 5. 1710 Nov. 6. 1723 Nov. 9. 1736 Nov. 10. 1740 Nov. 2. 1743 Nov. 4. . 1753 May 6. 1756 Nov. 6. 1769 Nov. 9. 6. 6. 2. 3. 1631 Nov. 1644 Nov. )661 Nov. 1661 May 1664 Nov. 4. 1674 May 6. 1677 Nov. 1690 Nov. 1697 Nov. 7. 9. 2. 1776 Nov. 1782 Nov. 1786 May 1789 Nov. 1799 May 1802 Nov. 1816 Nov. 11. 1822 Nov. 4. 1832 May 6. 2. 12. 3. 5. 7. 8. UArkcd on this diagram, and he will be enabled to noderstand more ettriljp What is meant by the inclination of the planets' orbits. It will be perceived on the dios^ram, that the inclination of Mercury's orbH to the plane of the ecliptic is 7° 9". These points of intersection are called the Nodes of the orbit. Mercury's ascending node is in the 16th degree of Taurus ; its descending node in the 16th degree' of Scorpio. As the Earth passes these nodes in November and May, the transits of Mercury must happen, for many ages to come, in one of these months. the time the first the present cen- 1835 Nov. 7. 1845 May 8. 1848 Nov. 9. IS61 Nov. 11. 1868 Nov. 4. 1878 May 6. 1881 Nov. 7. 1891 May 9. 1894 Nov. 10. By comparing the mean motion of any of the planets with the mean motion of the Earth, we may, in like manner, determine, the periods in which these bodies will return to the same points of their orbit, and the same positions with respect to the Sun. The knowledge of these periods will enable as to determine the hour when the planets rise, set, and pass the meridian, aitd io general, all the phenomena dependent upon the relative position of the Earth, the planet, and the Sun ; for at the end ol one of these periods they commence a^ain, and all recur in the same order. We have only to find a number of sidereal years, in which the planet completes exactly, or very nearly, a certain number of revolutions ; that is, to find such a number of planetary revolulionSi as, when taken together, shall be ezactlv equal to one, or any number of re- volutions of the Earth. In the case of Mercun^ this ralio will be, as 87.969 te to 365.256. Whence we find, that, 7 periodical revolutions of the Earth, are equal to 29 of Mercury : 13 periodical revolutions of the Earth, are equal to 54 of Mercury : 33 periodical revolutions of the £Iarth, are equal to 137 of Mercury ; 46 periodical revolutions of the Earth, are equal to 191 of Mercury. Therefore, transits of Mercury, at the same node, may happen at intervals of 7, 13, 33, 46, d;c. years. Transits of Venns, as well as eclipses of the Sun and Moon, are calculated upon the same principle. The sidereal revolution of a planet respects its absolute motion ; and Is measured by the time the planet takes to revolve from any fixed star to the same star again. The synodical revolution of a planet respects' its relative motion ; and is measured by the time that a planet occupies in coming back to the same posi- tion with respect to the Earth and the Sun. V The sidereal revolution of Mercury, is 87Q. 23h. 15m. 44s. 'Its synodical re- volution is found by dividing the whole circumference of 360<=> by its relative motion in respect to the Earth. Thus, the mean daily motion of Mercury is What are the points where the orbits of tlie planets intersect the orhit of tlie Earth call- ed 1 Where is Mercury's ascending node 7 where is its descending node? In what months must the transit of Mercury occur for many ages to come 7 Why must tiiey occur 10 tiiese m<»ith8 7 Hoio can we determine the periods in tofnt^ the planets will return to the same points of their orbits, and the same positions in respect to the Sun 7 Wh^ is it useful to know these periods 7 State the method of making the comptUatUm, What wiU the ratio be in the case of Mercury 7 State the reuio hettoeen the periodic au revolutions qfthe Earth and Mercury. At what intervals then may transits of Mercury at the same node happen 7 Upon what principle are transUs of Venus and eclfpses qfthe Sun and Moon, calculated 7 What U the sidereal resolution afm PUmet 7 What U the synodical revoluHmt 7 W?ua U the time of the sidereal r«»o» ittffofi qf Mercury 7 State jUte method of computing' Ou time qfthe eynoHeei nvo- tufntfaer f^uion. Compute the synodieal recohm lereury. , VENUS. 187 If732" .556 ; that of the Earth is 3&48'' J18 ; and their difference is IIU^T .237; hf iiig Mercury's relative motion, or what it gains on tiio Earth every day. Now by simple proportion, U184".237 is to 1 day, as 3GOO is to 115d. 21ii. 3', 25", tlia period of a eynodical revolution of Mercury. The absolute motion of Mercury in its orbit, is .109,757 miles an hour; that of the Earth, is 68,288 miles: thp diifercDce, 41,469 miles, is the mean relative motion of Mercury, with respect to the Earth. ^^' VENUS. There are but few persons who have not observed a beau- tiful star in the west, a little after sunset, called the evening star. This star is Venus. It is the second planet from the Sun. It is the brightest star in the firmament, and on this account easily distinguished from the other planets. If we observe this planet for several days, we shall find that it does not remain constantly at the same distance from the Sun, but that it appears to approach, or recede from him, at the rate of about three fifths of a degree every day ; and that it is sometimes on the east side of him, and sometimes on the west, thus continually oscillating backwards and for- wards between certain limits. As Venus never departs quite. 48° from the Sun, it is never seen at midnight, nor in opposition to that luminary ; being visible only about three hours after sunset, and as long before sunrise, according as its right ascension is greater or less than that of the Sun. At first, we behold it only a few minutes after sunset ; the next evening we hardly dis^ cover any sensible change in its position; but after a few days, we perceive that it has fallen considerably behind the Sua, and that it continues to depart farther and farther from him, setting later and later every evening, until the distance between it and the Sun, is equal to a little more than half the space from the horizon to the zenith, or about 46°. It now begins to return towards the Sun, making the same daily progress that it did in separating from him, and to set earlier and earlier every succeeding evening, until it final- ly sets with the Sun, and is lost in the splendour of his light. A few days after the phenomena we have now described, ^^^^^ ■ ■ ■ ■■ — — .1.— ., ■ ■■■ ■ ■ ■■■IM>l — l. ■■■■■■ ■ ■ .I^^^^M ■ I 1^ Whal b tlie rate per hour of tlie aliaolute motion of Mcicuiy in its orbit ? Of the Eai^ ? What is the mean relative motion of Mercury with respect to the Earth 7 What beautiful atar sometimes appears in the west a little after sunset 7 Wliat is the comparative dia long Describe its changes of position. IS8 TENDS. we perceive, m the mommg, near the eastern horizon, a bright star which was not visible before. This also is /enus, which is now called the morning star. It departs farther and farther from the Sun, rising a little earlier every day, until it is seen about 46° west of him, where it appears stationary for a few days ; then it resumes its course towards the Sun, appearing later and later every morning, until it rises with the Sun, and we cease to behold it. In a few days, the evening star again appears in the west, very near the setting-sun, and the same phenomena are again exhibited. Such are the visible appearances of Venus. Venus revolves about the Sun from west to east in 224j days, at the distance of about 68 millions of miles, moving ip her orbit at the rate of 80 thousand miles an hour. She turns around on her axis once in 23 hours, 21 minutes, and 7 seconds. Thus her day is about 25 minutes shorter than ours, while her year is equal to 7J^ of our months, or 32 weeks. The mean distance of the Earth from the Sun is estimated at 95 millions of miles, and that of Venus being 68 millions, the diameter of the Sun, as seen from Venus, will be to his diameter as seen from the Earth, as 95 to 68, and the surfaee of his disc as the square of 95 to the square of 68, tha-t is, as 9025 to 4626, or as 2 to 1 nearly. The intensity of light and heat being inversely as the squares of their distances from the 3un, Venus receives twice as much light and heat as the Earth. Her orbit is within the orbit of the Earth ; for if it were not, she would be seen as often in opposition to the Sun, as in conjunction with him; but sh^was never seen rising in the east while the Sun was setting in the west. Nor was she ever seen in quadrature, or on the meridian, when the Sun was either rising or setting. Mercury being about 23** from the Sun, and Venus 46°, the orbit of Venus must be outside of the Orbit of Mercury. The true diameter of Venus is 7621 miles; but her ap- parent diameter and brightness are constantly varying, ac- cording to her distance from the Earth. When Venus and the Earth are on the same side of the Sun, her distance In what direction, and in what time, does Venus revolve about the Sun ? What n ber ^stance from the Sun ? What is the rate per hour of ber motion in ber orbit 7 In dtm^ time does she revolve on her axis 7 How are the lengths of ber dajr and year, eomDoraa with thoseof tho Earth 1 How much laraer does the Sun appearat Venus than be does St the Earth 1 How much more light and beat does she recove from him, than the Earth} How much farther is Venus from tho Sun than Mercury 7 On which side of the oifaitof Mercury must ber oibit be? What ig her true diameter 7 In what proportioo do her ap- parent diameter and brightness constantly vary 7 What is her distance flwn the Eaita when they are both on the same side of the Sun 7 7ExtaL 189 from the Earth is only 26 millioas of miles ; when they are on opposite sides of the Sun, her distance is 164 millions of miles. Were the whole ot her enlightened hemisphere tmned towards us, when she is n~^rest, she would exhibit a light and brilliancy twenty-five times greater than she generally does, and appear like a small brilliant moon; but, at that time, her dark hemisphere is turned towards the Earth. When Venus approaches nearest to the Earth, her apparent^ or observed diameter, is 61'^2; when most remote, it is only 9".6 : now 6^^2-^9''.6 — Cf, hence when nearest the Earth her apparent diatc»leria 6| times greaf r than 'vhen most distant, and surface of her disc (C|)^, or nearly 41 times ^" eater, n this work, the apparent size of the heavenly bodies is estimated ft um the apparent surface of their discs, which Is always proporuonal to the sqcr^^es of their apparent diameters. When Venus' right ascension is less than that of the Sun, ' she rises before him ; when greater, she appears after his setting. She continues alternately morning and evening star, for a period of 292 days, each time. To those who are but little acquainted with astronomy, it will seem strange, at first, that Venus should apparently continue longer on the east or west side of the Sun, than the whole time of her periodical revolution around him. But it will be easily understood, when it is considered, that while Venus moves around the Sun, at the rate of about 1° 36' of angular motion per day, the Earth follows at the rate of 59'; so that Venus actually gains on the Earth, only 37' in a day. Now it IS evident that both planets will appear to keep on the same side of the Sun, until Venus has gained half her orbit, or 180^ in advance of the Earth; and this, at a mean rate, will require 292 days, since 292X37'= 10804', or 180° nearly. Mercury and Venus are called Inferior* planets, because their orbits are within the Earth's orbit, or between it and the Sun. The other planets are denominated Superior^ because their orbits are without or beyond the orbit of the * In almost all works on Astronomy, Mereory and Venus are denominated inferior planets, and the others, superior. But as these terms are employed, not to cxiwess the relative 9iz9of the planets, but to indicate their situation with respect to the Eaith, it would be better to adopt the terms interior and exterior. What is it when they are on opposite sides of the Sun? Which hemisphere is turned towards the Earth when she is nearest to us? Were her enlightened hemisphere turned towards us at th'it time, how would her light and brilliancy be compared with that wliich the generally exhibits, and what would bo Iier appearance ? What ia the length of her apparent diameter when she fs nearest to the Earth 't Whoi ia it when she ia moat remote 7 Hoio is the apparent size of a heavenly body eatimnted in this work 7 In what ciri^umstances does Venus rise befi>re, and in wnat set after, the dun 1 How loof does sbe continue, each time, alternately morning and evening star ? Why drtes she ai^ pear tonger on the east or west side of toe Son tlian the whole time of her periodical revo* lotion aronnd him? Why are Mercury and Venus called Inferior planets? Why an the other planets termed Superior plaaets ) 190 YERUS. Earth. [Plait /.] As the orbits of Mercury and Venus He leithtn the Earth's orbit, it is plain, that once in eirerf synodical revolution, each of these planets will be in cod* junction on the same side of the Sun. In the former case, the planet is said to be in its inferior conjunction^ and in the latter case, in its superior conjunction ; as in tne following figure. CONJUNCTION AND OPPOSITION OF THE PLANETS. Ttie period of Venas' synodicat revolution is found In the same manner as tliat of Mercury ; namely, by dividing the whole'circuraference of bor orbit by her mean relative motion in a day. Thus, Venus' absolute mean daily motion is 1® 36' 7".8, the Earth's is 69' 8".3, and their difference 36'e9".6. Divide 3eO° by 36' G9".6, and it gives 583.920, or nearly 684 days, for Venus' synodical revolution, or the period in which she is twice in conjunct tion with the Earth. Venus passes from her inferior to her superior coniunction in about 292 days. At her inferior conjunction, she is 26 millions of miles from the Earth ; at her superior conjanc- tion, 164 millions of miles. How oflen, in evt-rv synodical revolution, will each of these planets be in oonjunetkn on the same aide of the Sun that the Earth is I How often on the ouppoMte side l Ex* plain this. What names distinnitsb these two species of conjunction ) How U the «|f- nodteal revofutimt of Ventu found 1 Make the eateulation. How long is she in past* inf from her inferior to Iter superior oonjum^tion? How far is she from the Eaitln at bsr inCsior coiiiunctioo 1 How far at lior supeiior 7 7CND8. 191 It might be expected that her brilliancy would be propor? *ionally increased, in the one case, and diminished, in the other; and so it would be, were it not that her enlightened hemisphere is turned more and more from us, as she ap- proaches the Earth, and comes more and more into view as she recedes from it. It is to this cause aione that we must attribute the uniformity of her splendour as it usually ap- pears to the naked eye. Mercury and Venus present to us, successively, the v^arious shapes and appearances of the Moon ; waxing and waning through different phases, from the beautiful crescent to the full rounded orb. This fact shows, that they revolve around the Sun, and between the Sun and the Earth. Let the pupil endeavour to explain these phases on any other supposition, and he will be convin<;ed that the system of Ptolemy is erroneous, while that of Copernicus is confirmed. It should be remarked, ]iowe\cr, tliat Venufi is never »een when ske is entire* ly fulL except onct! or twice in a century, when she passes directly over the Bun's disc. At«vcry other conjunction, slie is either behind the Snn, or so near him as to be hidden by tlic 8|>lcndoMr of Itia light.^ The diagram on the ne:ct page will better illustrate tiic various appearances of VenuSi as she moves around the Sun, tlian any description of litem could do. From her inferior to her superior conjunction, Ventis ap- pears on the west side of the Sun, and is then our morning star ; from her superior to her inferior conjunction she ap- pears on the east side of the Sun, and is then our evening ^tar.^Y ' * Thojmincnt astronomer, Thomas Dick, LL. D.. well known m this eaaxAxy as the autlwr of tlie Cliristian Philosoylicr, Pkilosophy of a Pnturc 8tat«, 4kc., in a review oftUs remark, observes—" 'fhis ought not to Ixi laid down as a peecnd tnith. Aboat the year 1813, i made a great variety of oljscrvations on Venus in the day time, by an equatorial instrument, and found, that siie crnild be seen when only, 1^ 97' Irom the Sun's nuugin, and consequently tnaj/ bo seen at the moment of her superior runjunntjon, when lier geo- c<>ntric latitude, at that time, eguale or exceeds l^ 43*. 1 luve sfnne (iiint expectations of facinf able to see Venus, in the coarse of two or tlirce days, at her superior ooojunetioni tl'tJic weatlier be favoundile."— Afardt 3, i83l. Why is not her briHianey iiroportkmably increased in the fSMrmer case, and diminished ie the latter 7 What appearanoes do Mercury and Venus present to us at diffeient times 1 v> bat supposition is neeessary for the explanation of these i>hases 1 What system do they tend to refute 1 What system do they confirm 7 Hmo qften i» Vofta seen when the ie entirely fuU7 Why iaehe not aeen at the fuU teener 1 In what part of her or> bit does Vemisappearon the west side of the Sun) In what on the east 7 Inwhatperti is slie, alternately, moniinc and evening star 7 Sit. " .i S ' YEHUS, 193 Like Mercury, she sometimes seems to be statioriarjr. Her apparent motion, like his, is sometimes rapid ; at one time, direcL and at another, retrograde ; vibrating alternate- ly backwaras and forwards, from west to east, and from east to west. These vibrations appear to extend irom 45° to 47**, on each side of the Sun. Consequently she never appears in the eastern horizon, more than three hours before sunrise, nor continues longer in the western horizon, aAer sun- set. Any star or planet, therefore, however brilliant it may appear, which is seen earlier or later llian this, cannot be Venas. In passing from her western to her eastern elongation^ her motion is from west to east, in the order of the signs ; it is thence called direct motion. In passing from her eastern to her western elongation, her motion with respect to the Earth, is from east to west, contrary to the order of the signs ; it is thence denominated retrograde motion. Her motion appears quickest about the time of her conjunctions ; and she seems stationary, at her elongations. She is bright- est about 36 days before and after her inferior conjunction, when her light is so great as to project a visible shadow in the night, and sometimes she is visible even at noon-day. In the following %Ure, the outer circle represents the Earth's orbit, and the Inner circle, that of Venus, while she moves around the 8nn, in the orcler of the letters a, b, c, htt notncnon happen ? Why can it not hnppon oftener 7 State the nietliod of prcdietin£ U« iransitg of Veous. frtH+^-H. A.!b,t«.ttnn.nr.hl.ft«donUDOo.b..«»«dl,». eamnxni dlrlior, in muS oinldiilT ihem bj locti ouoibtn u will oialu on* • mutiipltof Iheothfr; nccordiiiglj'. ISumea Ibe ilenooilnuar win lis D(BrlT IB ; 291— f>y7— ass. uwiher period; and Hopn. Whence weflodlhu, *3 pertodlcal revoliirlana of I he Rarth, are < e uma Jefree u[ eaglllaniu. The Earth passes her asceadjng node ia the begJDning of Decemher, and her desceadiog node, in ihe beg'ioaiag of June. Hence, the transits of Venus, for ages to come, w" happen in Decembei: and June. The first transit e\ known to have been seen by any human being, took pla at the ascending node, December 4th, 1639.* If to tt date, we add 235 years, we shall have the lime oC the nc traosii at the same node, which will accordingly happen 1874. There will be another at the same node in 186 ; yibkb node, »iui whin, dii Ihc finlUorait of Va 105 TENO0 right years afterwards. It is not more certain that this phe- nomenon will recur, than that the event itself will engross the attention of all the astronomers then living upon the Earth. It will be anticipated, and provided for, and observ- ed, in every inhabited quarter of the glob^, with an inten- sity of solicitude which no natural phenomena, since the creation, has ever excited. The reason why a transit of Venus should excite so great an interest, is, because it may be expected to solve an im- portant problem in astronomy, which has never yet been satisfactorily done : — a problem whose solution will make known to us the magnitudes and masses of all the planets, the true dimensions of their orbits, their rates of motioQ around tbe Sun, and their respective distances from the Sun, and from each other. It may be expected, in short, to furnish a universal standard of astronomical measure. Another consideration will render the observation of this transit pe- culiarly favourable ; and that is, astronomers will be supplied with better instruments, and more accurate means of obser- vation, than on any former occasion. -1^ So important, says Sir John Herschel, have tlies« obaerratioas appeared to astronomers, that at the last transit of Venus, in 1769, expeditions were fitted out, on the most efficient scale, by the British, French, Russian, and other governments, to the remotest corners of the globe, for the express purposte of making them. The celebrated expedition of Captain Cook to Otaheite, was otic of them. The general result of all the observations made oa this most memorable occasion, gives 8".5776 for the Sun's horizontal parallax. The phenomena of the seasons, of each of tbe planets, like those of the Earth, depej;^ upon the inclination of the axis of the planet, to the plane of its orbit. The inclination of the axis of Venus to the plane of her orbit, though no! precisely known, is commonly estimated at 75® ; which is more than three times as great as the inclination of th^ Earth's axis to the plane of the ecliptic. The north pole of Venus' axis inclines towards the 20th degree of Aquarius ; the Earth's towards the beginning of Cancer ; consequently, the northern parts of Venus have summer in the signs where those of the Earth have winter, and vice versa. The declination of the Sun on each side of her equator, must be equal to the inclination of her axis ; and if this ex tends to 75°, her tropics are only 15° from her poles, and her polar circles 15" from hei equator. It follows, also, that Why will the next transit excite a very great and universal interest? Upon what do the IMienDmena of the seasons of each of the planets depend ) What is the estimated inclina* tion of the axis of Venus to tbe plane of her orbit 7 How does this inclination compare with that of the ('.orth's axis to the plane of the ecliptic 7 What seasons have the north- ern parts of Venus, wben those of the Earth have winter 7 How do we know this I To what must the declination of the Sun on each side of her equator be e^ial 7 How ftr urn ner tr >pics frum her poloa, and her polar cirdes from her equator ? YBNUfl. 167 tke Son must change his declination more in one day at VeoQs, than in five days on the Earth ; and consequently, that he never shines vertically on the same places for two days in succession. This may perhaps be providentially ordered, to prevent the too great effect of ihe Sun's heat, which, on the supposition that it is in inverse proportion to the square of the distance, is twice as great on this planet as it is on the Earth. At each pole, the Sun continues half a yeac* without set- ting in summer, and as long without rising in winter ; con- sequently, the polar inhabitants of Venus, like those of the earth, have only one day and one night in the year ; with this difference, that the polar days and nights of Venus are not quite two thirds as long as ours. Between her polar circles, which are but 15^ from her equator, there are two winters, two summers, two springs, and two autumns, every year. But because the Sun stays fur some time near the tropics, and passes so quickly over the equator, the winters in that zone will be almost twice as long as the summers. TELESCOPIC APPEARANCES OF VENDS. Fig. a When viewed through a good telescope, Venus exhibits not only all the moon- like phases of Mercury, but also a va- riety of inequalities on her surface ; dark spots, and brilliant shades, hills, and valleys, and elevated mountains. But on account of the great density of her atmosphere, these in- * Tbat is, halfqfVenut^ year, or 1« weeks. ■ ' < " ■ ■■■ ■ ■ ' 11 !■ • 111 1 •■ m^^m^ now much more must the Sun ehanfe his deeUnatioo in one day at Venus than on Um Ejutb? Why, perhaps, is this so ordered I How nanydays and nights have her polar inhabitants dannx the year ? How long are these days and nighU, cmapaied with thoM uf our polar inhabitants 7 How many, and what seasons, hns Venus, between ter polL. orcles ) What is the length of the winters in this a>ne, oooipared with uat of the sum- men I What appearances, besides her moon-Ue phases, does Venus exhibit when «-« throng a giMxiteleBoopcl 198 THE ftA^KTB. « eqaalities are perceived with more difficulty than those ap^ on the other planets. ^ The mountains of Venus, like those of Mercury and the Moon, are highest in the southern hemisphere. According to M. Schroeter, a celebrated German astronomer, who spent more than ten years in observations upon this planet, some of her mountains rise to the enormous height of from 10 to 22 miles.* The observations of Dr. Herschel do nol indicate so great an altitude ; and he thinks, that in genera) they are considerably overrated. He estimates the diame ter of Venus at 8,G49 miles ; making her bulk more than one sixth larger than that of the Earth. Several eminent astronomers affirm, that they have repeatedly seen Venus attended by a satellite, and they have given circumstantial details of. its size and appearance, its periodical revolution^ and its distance from her It is said to resemble our Moon in its phases, its distance, and its magnitude. Other astro- nomers deny the existence of such a body, because it was not seen with Venus on the Sun's disc, at the transits of 1761, and 1769, THE EARTH. The Earth is the place from which all our observations of the heavenly bodies must necessarily be made. The ap- parent motions of these bodies being very considerably af- fected by her figure, motions, and dimensions, these hold an important place iu astronomical science. It will there- fore be proper to consider, first, some of the methods by which they have been determined. . If, standing on the sea-shore, in a clear day, we view a ship leaving the coast, in any direction^ the hull or body of the vessel first disappears ; afterwards the rigging, and lastly, the top of the mast vanishes from our sight. Those on board the ship, observe that the coast ficst sinks below the horizon, then the buildings, and lastly the tallest spires of the city * lat, a8.«5 nukfl ; ad, 18.97 miles ; Sd, 11.44 miles ; 4th, 10.84 miles. Why is it mote difficalt to perceive the inequalities on her sarfaoe than those on thm other planets ? In which hemnphere are her mountains highest 7 What does M. Schroe- ter make the altitude of some or the highest 1 Is this estimate confiraied by the observa - tions of Dr. Hoschel ? How long is the diameter of Venus, according to Herschel's es- timate ? How much larger, then, must she be than the Earth 1 8ome astronomers affirnft that they have seen Venus attended by a satellite, why do otiicri deny the existence ^ such a body ) Vihy is it important, m an astronomical view, to be acquainted with ths figure, dimensions, and motions of the Earth } Mention sc»ae of the proofs of the coo- vexity of i!a soiawm } ( TBB BARTU. 199 wlneli they are learing. Now these phenomena are evi- dently caused hy the convexity of the water which is be- tween the eye and the object ; for, were the surface of the sea merely an extended plain, the largest objects would be visible the .ongest, and the smallest disappear first. CONVEXITY OP THE EARTH. Fig. 9. Again : navigators have sailed quite around the Earth, and thus proved its convexity. Ferdinand Magellan, a Portostiese, waa the first who carried this enterprise into ezecatioo. He embarkedfrom SeTille. in Spain, and directed his course towaids the vrest. After a long voyage, be descried the continent of Americcu Not fimfing an opening to enable him to continue his course in a westerly direction, he sailed along the coast towards the south, till, coming to its sou* I hern eztreinity, he sailed around it, and found himself in the grest Southern Ocean. He then resumed his course towards the west. Aller some time he arrived at the Molucca Islands, in the Eaatern Hemisphere ; and sailing con- tinually towards the west, he made Europe from the east ; arriving at the place from wiiich he set out.* The next who circumnavigated the Earth, was Sir Francis Drake, who sail* ed from Plymoulh, December 13, 1577, with five small vessels, and arrived at the same f>lace, September 26, 1580. Since that time, the circumnavigation of the Earth tws been performed by Cavendish, Cordes, Noort, Sharten. Here* mites, Dainpier, Woodes, Rogers, Schovten, Rog^ewin, Lord Anson, Byror^ Carteret, Wallis, Bougainville, Ck>ok, King, Clerk, Vancouver, and many others. These navigators, by sailing in a westerly direction, al- lowance being made for promontories, &c. arrived at the country they sailed from. Hence, the Earth must be either cylindrical or globular. It cannot be cylindrical, because, if so, the meridian distances would all be equal to each other, which is contrary to observation. The figure of the Earth is, therefore, spherical. The convexity of the Earth, north and south, is proved by the altitude of the pole, and of the circumpolar stars, ' — - - - — ■ - ■ * Masellan sailed from Seville, in Spain, Aocust 10, 1519, in the ship called the Vieto> S, accompanied by four other vi^snels. In April, 1S21, be waa killed in a skirmish itith e natives, at the island of Scbu, or Zebu, sometimes called Matan, one of the Fbinp- pjoes. One of his vessels, however, anrived at St. Lucar, near Seville, September 7, 1692. Who first sailed around the Earth ? Describe briefly his voyage. Who nextctr' eumnavigatedthe Earthl Describe Ms voyage. Mention the nam^ of some of tnos0 who hare since accomplished this enterprise. What may we infer fi wn the se fscts m jeiu4totiiefigureofthe Earhl How is the convodty ofoer suifaoe prevea} 200 THE &ART8. which is found unifonnly to increase as we approach theiDi while the inclination to the horizon, of the circles described by all the stars, ^adually diminishes. While proceeding in a southerly direction, the reverse of this takes place. The altitude of the p<51e, and of the circumpolar stars, con- tinually decreases; and all the stars describe circles whose inclination to the horizon increases with the distance. Whence we derive this general tru^h : The altitude of one pole, and the depression of the other, at any place oh the Earth's surface, is equal to the latitude of thai place. Another proof of the convexity of the earth's surface is, that the higher the eye is raised, the farther is the view ex- tended. An observer may see the setting sun from the top of a house^ or any considerable eminence, after he has ceas ed to be visible to those below. The curvature of the Earth for one mile is 8 inchea ; and this curvatare increases with the square of the distance. From this general law, it will be easy to calculate the distance at which any object whose height is given, may b« seen, or to determine the height of an object when the distance is Iiuowil 1st. To find the height of the object when the distance is given. Rule. F\nd thf. square of the distance inmiie*!, and take two thirds of thai number for the height in feet, Ex. 1. — How high must the e^e of an observer be raised, to see the BDrfac« of the ocean, at the distance of three miles 1 Arts. The square oi'3 ft., is 9 ft., and { of 9 fl. is 6 ft. Ex. 2. Suppose a person can jnst see the top of a spire over an extended plain often miles, how high is the steeple 1 Ans, The square of 10 is 100, and } of 100, is 66f , feet. 2. To find the distance, when the height is given. Rule. Increase the height in feet one half\ and extract the square root^for the distance^ in miles. Ex. 1 .—How far can a person see the surface of a plain, whose eye Is ele- vated six feet above it 1 Aru. 6, increased by its half, is 9, and tlie square root of 9 is 3 ; the distance is then 3 miles. Ex. 2.— To what distance can a person see a light-house whose height is 96 feet from the level of the ocean t Ans. £6 increased by its half, is 144, and the square root of 144 is 12 ; the distance is therefore 12 miles. 3. To find the curvature of the Earth when it exceeds a mile. RiTLK. Multiply the square of the distance by .000126. Although it appears from th»- preceding facts, that the Earth is .spherical, yet it is not a perfect sphere. If it were, the length of the degrees of latitude, from the equator to the Eoles, would be uniformly the same ; but it bas been found, y the most careful measurement, that as we go from the equator towards the poles, tbe length increases with the lati- tude. These measurements have been made by the most eminent raathematiciana ^ different countries, and in various places, from the equator to the arctto • — •— ■ ■ I ■■■ ■■■■ — ■ -I ■■■■■ ■■■_ „ _, ■■■ ^. M . ,, _■ ■■■■ ■ ^ To what is the convexity proportional 7 State the rule, deduced from this faett for finding the height of an object, tohen its distance from us is given. State the rule for finding the distance tvhen the height is given. State the rule for finding the curvature qr the Earth when the distance exceeds a mile. Is the fi^re of the Eazta an exact sphere I Were the Earth a perfi>ct Rphere, how would the leocth of tbe of latitude be, compared with each other } How are they, in fikct J riTCla. nwj lun finnd ihu ■ dfirac of lultuds « iha mile i IhU Ibe bcxt^oflbe Eulli wu uiDcs rouDded aoil convei betneea ll Plana if Obaenalim. I..,,,*. wsat »«-"■ Pern «8.732 Bau(u>rr. 68.896 MuoD UK) Uizon. G9.$9S BoECDTfch and I.emair*. Ea.OM U«lambre>ndMccbdiL K ..»:s.-,. These measuremenis proTC ihe Earth to be an oblate epheroid, whose loDgest or equatorial diameter is 7924 miles, and polar diameter, 7898 miles. Th:: mean diameter is, therefore about 7912j and their difference 26 miles. The French Acadiimf hare determined that the mean diameter of the Earth, Irom Ihe 43th decree of north latitude, to the opposite degree of south latitude, is accwatett/ 7912 miles. The Earth, considered as a planet, occupies a favoured rank in Ihe Solar System. It pleased the All-wise Crea- tor to assign its position among the heavenly bodies, where Dearly all the sister planets are visible to the naked eye. It is situated next to Veni .•-.-.-.. Sun. s, and is the third planet rroia the 202 THS BABTB, For what can appear more anUke, than the Earth, with her TasC and seemfngly Immeasurable extent, and the stars, which appear but as points 1 The £arth Is dark and opac|ue, the celestial bodies are brilliant. We perceive in it nc motion ; while in them we observe a continual change of place, as we view them at different hours of the day or night, or at different seasons of the year It moves round the Sun, from west to east, in 365 days 5 hours, 48 minutes, and 48 seconds ; and turns, the saini way, on its axis, in 23 hours, 56 minutes, and 4 seconds The former is called its annual motion, and causes the vicissitudes of the seasons. The latter is called its diurnal motion, and produces the succession of day and night. The Earth's mean distance from the Sun is about 95 millions of miles. It consequently moves in its orbit at the mean rate of 68 thousand miles an hour. Its equatorial di- ameter being 7924 miles, it turns on it^s axis at the rate of 1040 miles an hour. Thus, the earth on which we stand, and which has serv- ed for ages as the unshaken foundation of the firmest struc- tures, is every moment turning swiftly on its centre, and, at the same time, moving onwards with great rapidity through the empty space. This compound motion is to be understood of the whole earth,vrith all that it holds within its substance, or sustains upon its surface — of the solid mass beneath, of the ocean which flows around it, of the air that rests upon it, and of the clouds which float above it in the air. That the Earth, in common with all the planets, revolves around the Sun as a centre, is a fact which rests upon the clearest demonstrations of philosophy. That it revolves, like ihem, upon its own axis, is a truth which every rising and setting sun illustrates, and which very many phenomena concur to establish. Either the Earth moves around its axis every dayj or the whole universe moves around it in the same time. There is no third opinion, that can be formed on this point. Either the Earth must revolve on its axis every 24 hours, to pro- duce the alternate succession of day and night, or the Sun, Moon, planets, comets, fixed stars, and the whole frame ot the universe itself, must move around the Earth, in the same time. To suppose the latter case to be the fact, would be to cast a reflection on the wisdom of the Supreme Architect, whose laws are universal harmony. As well might the beetle, that in a moment turns on its ball, imagine the heav- What revolutionB does it perform, and in what direction } What is the time occncned in each of these revolutions l Bv what terras are these revolutions distinguished, ana what important efiects do they proauce? What u the Earth's mean distaooe from the Sun] what ia the mean rate or its motion in its orbit per hour 7 What is the rate of its vevolit* tion on its axis per hour 2 What are the ptswfs, that ^ perfimns these two revohitions ) rUfi EARTH. 203 ens and the Earth had made a revolution in the same instant. It is evident, that in proportion to the distance of the ce- lestial hodies from the Earth, must, on this suppositi|»n, be the rapidity of their movements. The Sun, then, would move at the rate of more than four hundred thousand miles in a minute ; the nearest stars, at the inconceivable velocity of 1400 millions of miles in a second; and the most distant luminaries, with a degree of swiftness which no numbers could express, — and all this, to save the little globe we tread upon, from turning safely on its axis once in 24 hours. The idea of the heavens revolving about the Earth, is en- cumbered with innumerable other difficulties., We will mention only one more. It is estimated on good authority, that there are visible, by means of glasses, no less than one hundred millions of stars, scattered at all possible distances in the heavens above, beneath, and around us. Now. is it in the least degree probable, that the velocities of all these bodies should be so regulated, that, though describing circles BO very different in dimensions, they should complete their revolutions in exactly the same time. In short, there is no^more reason to suppose that the heav- ens revolve around the Earth, than there is to suppose that they revolve around each of the other planets, separately, and at the same time ; since the same apparent revolution is common to them all, for they all appear to revolve upon their axis, in different periods. The rotation of the Earth determines the length of the day, and may be regarded as one of the most important el- ements in astronomical science. It serves as a universal measure of time, and forms the standard of comparison for the revolutions of the celestial bodies, for all ages, past and to come. Theory and observation concur in proving, that among the innumerable vicissitudes that prevail throughout creation, the period of the Earth's diurnal rotation is immu • table. The Earth performs one complete revolution on its axis in 23 hours, 56 minutes, and 4.09 seconds, of solar time This is called a sidereal day, because, in that time, the stars appear to complete one revolution around the Earth. But, as the Earth advances almost a degree eastward in its orbit, in the time that it turns eastward around its axis, it is plain that just one rotation never brings the same me- ridian around irom the Sun to the Sun again ; so that the Earth requires as much more than one complete revolution What important purposes does the peiiod of the Earth's rotation serve 7 What is a al* dtKaldbjl What is a solar day ] 204 THE EARTB. on its axis to complete a solar day^ ^ it has gone forward in that time. Hence in every natural or solar day, the Earth performs one complete revolution on its axis, and the 36dth part of another revolution. Consequently, in 365 Kays, the Earth turns 366 times around its axis. And as every revolution of the Earth on its axis completes a side- real day, there must be 366 sidereal days in a year. And, generally, since the rotation of any planet about its axis h the length of a sidereal day at that planet, the number of sidereal days will always exceed the number of solar days, by one, let that number be what it may, one revolution be- ing always lost in the course of an annual revolution. This dinerence between the sidereal and solar days may be il- ustrated by referring to a watch or clock. When both nands set out together, at 12 o'clock for instance, the minute hand must travel more than a whole circle before it will overtake the hour hand, that is, before they will come into conjunction again. In the same manner, if a man travel around the Earth eastwardly, no matter in what time, he will reckon one day m^re, on his arrival at the place whence he set out, than they do who remain at rest; while the man who travels arround the Earth westwardly will have onedayless. From which it is manifest, that, if two persons start from the same place at the same time, but go in contrary directions, the one travelling eastv^rd and the other westward, and each goes completely around the globe, although they should both arrive again at the very same hour at the same place from which they set out, yet they will disagree two whole days in their reckoning. Should the day of their return, to the man who travelled westwardly, be Monday, to the man who travelled eastwardly, it would be Wednesday ; while to those who remained at the places itself, it would be Tuesday. Nor is it necessary, in order to produce the gam or loss of a day, that the journey be performed either on the equa- tor, or on any parallel of latitude ; it is sufficient for the purpose, that all the meridians of the Earth be passed through, eastward or westward. The time, also, occupied in the journey, is equally unimportant ; the gain or loss of a day heing the same, whether the Earth be travelled around in 24 years, or in as many hours. What part of a second revolution docs the Earth complete in every solar day 7 How many times, then, does it turn on its axis in 965 days ) How many siifereai ua>'s are tfaera in a year? On any planet, what is the number of the sidereal days compared with the number of the solar? Illustrate the difiercncc between the sidereal and solar dayk by i» ferring to a watch or clock. Illustrate it by roferrtnic to two travellers goinf arounu thtt globe, one eastwardly and the other westwardly. TBE EARTH. 205 It is also evident, that if the Earth turned around its axis but once in a year, and if the revolution was performed the same way as its revolution around the Sun, there would be perpetual day on one side of it, and perpetual night on the other. From these facts the pupil will readily comprehend the principloji involved in a curious problem which appeared a few years ago : It was gr^tsvf report* ed by an American ship, that, in saiiin/^ over the ocean, it chanced to find aix Sundays in February. The fact was insisted on, and a solution demanded. There is nothing absurd in this. — The man who traveLs around the Earth eeut' wardly, will see the Sun go down a little earlier every succeeding day, than if he had remained at rest ; or earlier than they do who live at the place from which he set out The faster he travels towards the rising sun, the sooner will it appear above the horizon in the morning, and so much sooner will it set in the evening. What he thus gains in time^ will bear the same proportion to a solar day, as the distance travelled does to the circumference of the Eartli. — As the fflobe is 360 degrees in circumference, the Sun will appear to move over one twenty-fourth part of its surface, or 14°, every hour, which is 4 minutes to one d«^ree.— Consequently, the Sun will rise, come to the meii* dian, and set, 4 minutes sooner, at a place 1° east of us, than it will with us j at tlie distance of 2*=* the Sun will rise and set 8 mhiates sooner ; at the diff- lance of 3°, 12 minutes sooner, and so on. Now the man who travels one degree to the east, the first day, will have the Son on his meridian 4 minutes sooner than we do who are at rest ; and the second ckiy, 8 minutes sooner, and on the third day, 12 minutes sooner, and so on ; each successive day being completed 4 minutes earlier than the prcced* ing, until he arrives again at the place from which he started ; when this con* tinual gain of 4 minutes a day will have amounted to a whole dav in advance of our time ; he having seen the Sun rise and set once more than we have. Conseouently, the day on which he arrives at home, whatever day of the week it may oe, is one day m advance of ours, and he must needs live that day over again, b^ calling the next day by the same name, in order to make the accounts harmonize. If this should be the last day of February in a bissextile year, it would also be the same day of the week that tlie first was, and be six times repeated and if it should happen on Sunday, he would, under these circamstanccs. have six Sundays in February. Again : — Wherea^he man who travels at the rate of one degree to the east will have all his dayl 4 minutes shorter than ours, so, on the contrary, the man who travels at the same rate towards the west, will have all his days ( minutes longer than ours. When he has finished the circuit of the Earth and arrived at the place from which he first set out, he will have seen the Sun rise and set once /cm than we have. Consequently, the day he gets home wiD be one day after the time at that place : for which reason, if he arrives at home on Saturday, according to his own account, he wilUiave to call the next day Monday ; Sunday having gone by before he reachra home. Thus, on wliatever day of the week January should end, in common years, he would find the same day repeated only three times in February. If Jeunuary cndcrtea some years ago by an American sfdp, that in sailing over the ocean, Ufimni tits Buaiaus m Fetruary; pletue explain this. Why are the lidercal days alwsy* of the tame length 9 What are the canaes of tiie diflmeoee in tlw leoffth of tl« iolar daysl 206 TBC £ARTB« inclination of the Earth's axis to its orbit, and the inequa.itj of its motion around the Sun. From tnese two causes it is. that the time shown by a well regulated clock and that 01 a true sun-dial are scarcely ever the same. The difference between them, which sometimes amounts to 16 j- minutes, is called the^gua/ton q/* 7\'me, or the equation of solar days. f:l.\ The (.(Terei^e between mean and apparent time, or, in other words, be- tween Etjuinoctial and Ecliptic time, may be further shown by Figure 11, which represents the circles of the sphere. Let it b« first premised, that equinoctical time is clock time; and that eelijMc time is solar or apparent time. It appears, that from Aries to Cancer, the sun in the ecliptic comes to the meridian (.ejure the equinoctial sun ; from Cancer to Libra, after it; from Libra to Capricorn, be/ore it ; and from Capricorn to Aries, after it. If we notice what months the Sun is in these several quarters, we shall find, that from the 25ihof December to the 16th of April, and from the 16th of June to the 1st of September, the clock is faster than the sun-dial ; and that, from th« I6th of April to the 16th of June, and fh>m the Ist of September to tbe2Sch of December,' the sun-dial is faster than the clock. EQUATION OF TIME. Fig. 11. It is a universal fact, that, while none of the planets are perfect spheres, none ot their orbits are perfect circles. The planets all revolve about the Sun, in ellipses of different degrees of eccentricity ; having the Sun, not in the centre of the ellipse, but in one of its foci. «.^52** fS "***"' ^'JiSJ^P!^'9^' e volution, a planet passes throngli its perihelion and aphelion. The eccentri- city of the Earth's orbit is about one and a half millions of miles ; hence she is three millions of miles nearer the Sun in her perihelion, than in her aphe* lion. Now as the Sun remuns fixed in the lower focus of the Earth's orbit. It ia easv to perceive that a line, passing centrally through the Sun at right angles with the longer axis of the orbit, will divide it into two unequal segments. Precisely thus it is divided by the equinoctiai. That portion of the Earth's orbit which lies above the Sun, or north of the equinoctial, contains about 184 degrees ; while that portion of it which lies below the Sun, or south of the equinoctial, contains only 176 degrees. This fact shows why the Sun continues about 8 days longer on the north side of the equator in summer, than it does on the south side in winter. The exact calculation, for the year 1830, is as follows : d. h. m. From the vernal equinox to the summer solstice, —92 21 19 ? d. h. m. From the summer solstice to the autumnal equinox, —93 14 1 ^ l^ It, 19. From the autumnal equinox to the winter solstice, —89 17 17P d. li. m. From the winter solstice to the vernal equinoj^ —89 1 13 S 178, 18,30. Difference in favour of the north side, — '^7, 16, 49. The points of the Earth's orbit which correspond to its greatest and least distances from the Sun, are called, the former tne Apogee, and the latter the Perigee; two Greek words, the former of Avhich signifies /rowi the Earthy and the latter qpout the Earth. These points are also designated by the common name of Apsides. [See these points represented^ Plate I.] The Earth being in its perihelion about the the 1st of Janu- ary, and in its aphelion the 1st of July, we are three millions of miles nearer the Sun in winter than in midsummer. The reason why we have not, as might be expected, the hottest weather when the Earth ii nearest the Sun, is, because the What is the eccentricitif of an orbit ? Hvio many times i$ a planet in its aphe- lion, and hmo rnany in its perihelion, in every revolinion ? Itots much fartfter is it from the Sun in the former case than in the latter 7 In which focus of the Eirth's orbit is the Sun 7 How does the equinoctial divide the Earih'e orbit 7 Why does the Sun remain longer on the north side of the cqaator in summer, tiian itdtiea on the south side in winter ? What are. the Earth's Apogee and Perigee 7 By what common name are these ttdo points designated 7 When is the Earth in ito Perihebon j When in its Aphelion ? Are we nearer the Sun in summer than in winter? How much Bearer, are we in winter than in sununer 7 Why do we not have the hottest, woaltej *vben we are nearest the Sun 7 tOS TUB MOOK. San, at that time, having retreated to the southern tropic, shines so obliquely on the northern hemisphere, that its rays have scarcely half the eflect of the summer Sun ; and con- tinuing but a short time above the horizon, less heat is ac- cumulated by day than is dissipated by night. As the Earth performs its annual revolution around the^ Sun, the position of its axis remains invariably the same ; always pointing to the North Pole of the heavens, and al- ways maintaining the same inclination to its orbit. This seems to be providentially ordered for the benefit of man- kind. If the axis of the Earth always pointed to the centre of its orbit^ all external objects would appear to whirl aboat our heads m an inexplicable maze. Nothing would appear permanent. The mariner could no longer direct his course Dy the stars, and every index in nature would mislead us. THE MOON. There is no object within the scope of astronomical ob- servation which affords greater variety of interesting inves- tigation than the various phases and motions of the Moon. From them the astronomer ascertains the form of the Earth, the vicissitudes of the tides, the causes of eclipses and oe- cultatioQs, the distance of the Sun, and, consequently, the magnitude of the solar system. These phenomena, which are perfectly obvious to the unassisted eye, served as a stand- ard of measurement to all nations, until the advancement of science taught them the advantages of solar time. It is to these phenomena that the navigator is indebted for that precision of knowledge which guides him with well grounded confidence through the pathless ocean. The Hebrews, the Greeks, the Romans, and, in.general. all the ancients, used to assemble at the time of new or full Moon, to discharge the duties of piety and gratitude for her unwearied attendance on the Earth, and all her manifold uses. When the Moon, after having been in conjunction with the Sun, emerges from his rays, she first appears in the evening, a little after sun-set, like a fine luminous crescent, with its convex side towards the Sun. If we observe her A,s the Earth revolvos about the Sun, what is the position of its axis 7 Should it« axis •IwajTR point to the centre of its orbit, how would external objects appear to us 7 What important purposes does tiie Moon serve to the astronomer ) Of what importance are her phenomena to the navigator? What nations used to assemble at the time of the new or rf the ftiU Moon, to express their gratitude ftv her benefits? Describe the oppuent motte •I the Moon, and her phases. "^ TBE MOON. 209 tbe next evening, we find her about 13^ farther east of the Sun than on the preceding evening, and her crescent of lij;ht sensibly^ augmented. Repeating these observations, we per- ceive that she departs farther and farther from the Sun, as her enlightened surface comes more and more into view, un- til she arrives at her first quarter, and comes to the meridian at sun-set. She has then finished half her course from the new to the full, and half her enlightened hemisphere is turn- ed towards the Earth. After her first 'luarter, she appears more and more gib- bous, as she recedes farther and farther from the Sun. until she has completed just half her revolution around the Earth, and is seen rising in the east when the Sun is setting in the west. She then presents her enlightened orb full to ouc view, and is said to be in opposition j because she is then uu the opposite side of the Earth with respect to the Sun. In the first half of her orbit she appears to pass over out heads through the upper hemisphere; she now descends be- low the eastern horizon to pass through that part of her or- bit which lies in the lower hemisphere. After her full she wanes through the saxAe changes of ap- pearance as before, but in an inverted order ; and we see hei m the morning like a fine thread of light, a little west of the rising-sun. For the next two or three days she is lost to our view, rising and setting in conjunction with the Sun j after which, she passes over, by reason of her daily motion, to the ecLst side of the Sun, and we behold her again a new Moon, as before. In changing sides with the Sun, she changes also the direction of her crescent. Before her con- junction, it was turned to the east; it is now turned towards the west. These different appearances of the Moon are called her phases. They prove that she shines not by any light of her own ; if she did, being globular, we should al- ways see her a round full orb like the Sun. The Moon is a satellite to the Eaith. about which she re- volves in an elliptical orbit, in 29 days,' 12 hours, 44 min- utes, and 3 seconds: the time which elapses between one new moon and another. This is called ner synodic revo- lution. Her revolution from any fixed star to the same stai again, is called her periodic or siderial revolution. It i> accomplished in 27 days, 7 hours, 43 minutes, and 11 J- sec- onds ; but in this time, the Earth has advanced nearly as many degrees in her orbit ; consequently the Moon, at the How 19 it known that the Moon does not shine by her own light 7 About what does the Moon revolve, and what is the figure of her orbit J What is the time of her revolution firorti one new Moon to another 1 What is this revolution deiiominated ? What u her iw riodic or sidereal revolution ? In what time i* this accomplished } 18* 210 TBEMOOlf. «Dd of one complete revolution, must go as many degpeee farther, before she will come again into the same position with respect to the Sun and the Earth, r - The Moon is the nearest of all the heavenly bodies, being about 30 times the diameter of the Earth, or 240^000 miles, distant from us. Her mean daily motion, in her orbit, is nearly 14 times as great as the Earth's ; since she not only Accompanies the Earth around the Sun every year, but, in the meantime, performs nearly 13 revolutions about the Earth. AlUiongh the apparent motion of the Moon, in her orbit, is greater than \zaX of any other heavenly body, since she passes over, at a mean rate, nu less than 13° 10' 35" in a day ; yet this is to be understood as angular motion — motion in a small orbit, and therefore embracing a great number ofdeffreet^ •od but comparatively few miles. As the Moon, while revolving about the Earth, is carried with it at the same time around the Sun, her path is ez- tremeljT irregular, and very different from what it seems to Oe. Like a point in the wheel of a carriage, moving over a convex road, the Moon will describe a succession of epicycloidal curves, which are always concave towards the Sun; not very unlike their presentation in the following figure. THE moon's motion* Fig. 12. To what b the di%t>noe of turn in thcM two levolatiaas owina 7 How great is the distance of the Moon from the Earth, compared with tl»t of the otLer heavenly bodiea J What ix lier distance from us 7 What is, her motion in her oiWt, compared with tlaa SUft^ ? How many tmiM does she revolve aromid the Eartll, every year? The mppm- rent motion qfthe Moon U freaier in iter orlUthm that ofanu other heavmlv hoST* THE Moon. SU Let Ad b B represent a portion of the Eanh*s orbit ; and a b e d 9 thn Icnaf orbit. When the Earth Is at b^ the new Moon ia at a ; and while the Earth ia moving from b to ita poaition as repreaented in the fig are, the Moon has moved through half her orbit, from a to c, where she is full ; so whUe the Earth is moving from its present position to d, the Moon describes the other half of her orbit from e to e; where she is agaJo in conjunction. The Mood, though apparently as large as the Sud, is the smallest of all the heavenly bodies that are visible to the naked eye. Her diameter is but 2162 miles ; consequently her surface is 13 times less than that of the Earth, and her bulk 49 times less. It would require 70 millions of such bodies to equal the volume of the Sun. The reason why she appears as large as the Sun, when, in truth, she is so much less, is because she is 400 times nearer to us than the Sun. The Moon revolves once on her axis exactly in the time that she performs her revolution around the Earth. This is evident from her always presenting the same side to the Earth ; for if she had no rotation upon an axis, every part of her surface would be presented to a spectator on the Earth, in the course of her synod ical revolution. It follows, then, that there is but one day and night in her year^ con- taining, both together, 29 days, 12 hours, 44 minutes, and 3 seconds. As the Moon turns on her axis only as she moves around the Earth, it is plain that the inhabitants of one half of the lunar world are totally deprived of the sight of the Earth, •unless they travel to the opposite hemisphere. This we may presume they will do, were it only to view so sublime a spectacle ; for it is certain that from the Moon the Earth appears ten times larger than any other body in the universe. As the Moon enlightens the Earth, by reflecting the light of the Sun, so likewise the Earth illuminates the Moon, ex- hibiting to her the same phases that she does to us, only in a contrary order. And, as the surface of the Earth is 13 times as large as the surface of the Moon, the Earth, when full to the Moon, will appear 13 times as large as the full moon does to us. That side of the Moon, therefore, which is towards the Earth, may be said to have no darkness at all, the Earth constantly shining upon it with extraordinary splendour when the Sun is sibsent ; it therefore enjoys suc- cessively two .weeks of illumination from the Sun, and two What ii ber magnitude, eompaied with that of the other lieavenly bodiei 1 ^Wbat is her diameter? How great are her sur&ce and her ImiIIc, compared with thoae ofthe JBarn I How many such bodies would it require to equal the volume m the Son 1 Wh^ does MB appear as lanse as the Sun, when in reality she is so much less 7 What uu*^ tuneoT bsr ravolutionon her axis, compared with that of her revolution around the Eartb 1 How ia (his proved ? How many days and nights then has she in the course of her •raog>«J n^ volntion ? Wliat is the leiMth of both united? Descnbe the phenomena of the Eaitliaa •een by the inhabitants of the Moon. 213 THE MOO If. weeks of earth-light from the Earth. The other side of the Moon has alternately a fortnight's light, and a fortnight's darkness. As the Earth revolves on its axis, the several continents, seas, and islands, appear to the lunar inhabitants like so many spots, of different forms and brightness, alternately moving over its surface, being more or less brilliant, as they are seen through intervening clouds. By these spots, the lunarians can not only determine the period of the Earth's rotation, just as we do that of the Sun, but they may also find the longitude of their places, as we find the latitude ot ours. As the full Moon always happens when the Moon is di- rectly opposite the Sun, all the full Moons in our winter, must happen when the Moon is on the north side of the equi- noctial, because then the Sun is on the south side of it ; con- sequently, at the north pole of the Earth, there will be a fortnight's moon-light and a fortnight's darkness by turns, for a period of six months, and the same will be the fact du- ring the Sun's absence the other six months, at the south pole. The Moon's axis being inclined only about 1^° to her orbit, she can have no sensible diversity of seasons ; from which we may infer, that her atmosphere is mild and uni- forfaa. The quantity of light which we derive from the Moon when full, is at least 300 thousand times less than that of the Sun.* When viewed through a good telescope, the Moon pre- sents a most wonderful and interesting aspect. Besides the large dark spots, which are visible to the naked eye, we perceive extensive valleys, shelving rocks, and long ridges of elevated mountains, projecting their shadows on the Elains below. Single mountains occasionally rise to a great eight, while circular hollows, more than three miles deep, «eem excavated in the plains. Her mountain scenery bears a striking resemblance to the towering sublimity and terrific rug^edness of the Alpine re- * This is Mons. Bouqacr's inference, from his experiments, as stated bjr La Place, in las work, p. 43. I'be result of Dr. Wollaston's computations was diflbrent Professor Leslie makes the light of the Moon 150,000 times less than that of the Sun : it was fininer- y reckoned 100,000 times less. As the Earth revolves on its axis, how do its continents, seas, and islands, appear to the lunar inhabitHnts? For what purposes may these spots serve to the lunarians ? What are the periods of the Moon's presence and aUcnce to the polar inhabitants ? Explain this. Why,cannot the Moon have any sensible diversity ofseasons ? What then may we infer to be the character of her atmosphere? What is the quantity of fight wWch «Je aiftrds when full, compared wth that of the 8un ) Describe the appearance of tlie Moon when seen through a good telescope. What mountains of tlie Eartli does Iwr mountam scenery resemble 7 THfi Moon. HI |{;kfm9. or of the Appenines, after which some of her moan- tains nave been named, and of the Cordilleras of our own continent. Hu^e masses of rock rising precipitouslv from the plains, lift their peaked summits to an immense neight in the air, while shapeless crags hang over their projecting sides, and seem on the eve of being precipitated into the tremendous chasm below. Around the base of these frightful eminences, are strewed numerous loose and unconnected fragments, which time seems to have detached from their parent mass ; and when we examine the rents and ravines which accompany the overhanging cliffs, the behoHer expects every moment that they are to oe torn from their base, and that the process of destructive separation which he had only contemplated in its effects, is about to be exhibited before him in all its reality. The range of mountains called the Appenines, which tra- verses a portion of the Moon's disc from north-east to south- west, and of which some parts are visible to the naked eye, rise with a precipitous and craggy front from the level of the Mare Jmbrium, or Sea of showers.* In this extensive range are several ridges whose summits hav^ a perpendicu- lar elevation of four miles, and more ; and though they often descend to a much lower level, they present an inac- cessible barrier on the north-east, while on the south-west they sink in gentle declivity to the plains. There is one remarkable feature in the Moon's surface which bears no analogy to any thing observable on the Earth. This is the circular cavities which appear in every part of her disc. Some of these immense caverns are nearly four miles deep^ and forty miles in diameter. They are most numerous m the south-western part. As they reflect the Sun's rays more copiously, they render this part of her surface more brilliant than any other. They present to us nearly the same appearance as our Earth might be sup- posed to present to the Moon, if all our great lakes and seas v/ere dried up. The number of remarkable spots on the Moon, whc^fl latitude and lon^ritude have been accurately determinedy exceeds 800. The number of seas and lakes, as they were formerly considered, whose length and breadth are known, ^ - I ■ . . If I II ■ ^- * Tbc name of a lunar spot. Deacribe the appearance of her mountaini. On what part of her disc is that ranie of mountains called the Appenines, situated ? Describe it. What remarkable feature in dw Moon's surface, bears no analogy to any thing observable on the Earth's suiiaM? Descrtba their appearance. What is the number of remarkable spots in the Moon's surface, wbw* latitude and longitnde have been accumtely determined J What is the number or anu and Utes. at their were 6rn>orly consiilered. whose dimenskmi are known * ^4 TRC MOOlf. 18 between 20 and 30; while the number of peaks and mountains, whose perpendicular elevation vanes from a fourth of a mile to five miles in height, and whose bases are from one to seventy miles in length, is not less than one hundred and fifty ."^^ Graphical views of these natural appearances, accompanied with minute and ifuniUar descriptions, constitute wtiat is called Settnograpky^ from two Greek words, which mean the same thing in regard to the Moon, as Geog- raphy does in regard to the Earth. An idea of some of these scenes may be formed by con- ceiving a plain of about 100 miles in circumfereuce, encircled by a range of mountains, of various forms, three miles in perpendicular height, and having a mountain near the centre, whose top reaches a mile and a half above the level of the plain. From the top of this central mountain, the whole plain, with all its scenery, would be distinctly visible, and the view would be bounded only by a lofty ampnitheatre of mountains, rearing their summits to the sky. The bright spots of the Moon are the mountainous regions ; while the dark spots are the plains, or more level parts of her surface. There may be rivers or small lakes on this planet ; but it is generally thought, by astrono- mers of the present day, that there are no seas or large col- lections of water, as was formerly supposed. Some of these mountains and deep valleys are visible to the naked eye ; and many more are visible through a telescope of but moderate powers. A telescope which magnifies only 100 times, will show a spot on the Moon's surface, whose diameter is 1223 yards ; and one which magnifies a thousand times, will enable us to perceive any enlightened object on her surface whose di- mensions are only 122 yards, which does not much exceed the dimensions of some of our public edifices, as for instance, the Capitol at Washington, or St. Paul's Cathedral. Pro- fessor Frauenhofer, of Munich, recently announced that he had discovered a lunar edifice, resembling a fortification, together with several lines of road. The celebrated as- tronomer Schroeter, conjectures the existence of a great * Brewster's Selenography. The best maps of the Moon hitherto published, are those bjr Sciiroeter; but the most curi(Mi8 and complete representation of the telescopic and na- tural appearances of the Moon, is to be seen on Russei's Lunar Globe. See also SOeno- grapMa, by C. Blunt. What is the number of peaks and mountains whose perpendicular elevation varies from t^ii!^. e^/I""^*** fc 5™^'^^' *"^ ^y,\*^^ ^?»®8 »re from one to seventy miles in length J WTiat U Selenography 1 Give an illustration to enable us to form some i^tea of some of these scenes. Which spots are the mountainous regions, and which the plains? Do as- SS,"M!^!f.»"?i!!« !i''^*' *^ ^^'ey did formerly, that there are large collections of water on ECUPbcIS. 315 eity on the east side of the Moon, a little north of her equator, mi extensive canal in another place, and fields of vegeta- •ton in another. SOLAR AND LUNAR ECLIPSES. Op all the phenomena of the heavens, there are none rhich engage the attention of mankind more than eclipses if the Sun and Moon; and to those who are unacauainted «7ith astronomy, nothing appears more wonderful than the accuracy with which they can he predicted. In the early iges of antiquity the^ were regarded as alarming devia- tions from the established laws of nature, presaging great public calamities, and other tokens of the divine displeasure. In China, the prediction and observance of eclipses are made a matter of state policy, in order to operate upon tlie fears of the ignorant, and impose on I hem a superstitious regard for the occult wisdom of their rulers. In Mexico, the natives fast and aiSict themselves, during eclipses, under an apprehen* sion that the great spirit is in ■ ■ ■ In what direction does every planet of the Bolar system cast a shadow 7 What is this shadow, and to what is it proportional 1 If the Sun and planet were both of the same inagnitade, what would be the form of the shadow, and its diameter t If the planet were tarffer than the San, what would be the forei of the shadow } But as the Sun ia much wnier than any of the planets, what must be the form of their shadows, and to what etn tbey proportional 7 Whv can no one of the primary planets eciipae another 7 Est' friam Aoto, on certain oceaHona, they may e^ipee their satellitee, and on others b€ eff,ipeed by them. When the Sun is at his greatest distance from the Earth, and thd 5!Sf?iH '^ toMi dMtance, how far wiU her shadow extend 1 When the Sun ia at hip 22IlL?liSiSS2Li?* ft*.i2!^.** hergiweir? When the Sun and Moon an bothattfa to represent a part of the Earth's orbit, and the Moon's shadow to termi* nate at the vertex V. The small space between e^will represent the breadth of the inminous ring which will be visible all around the darlc body of the Moon. Such was the eclipse of February 12, 1831, which passed over the southern states from 8. W. to N. E, It was the only annular eclipse ever visible in the United States. Along the path of this eclipse, the luminous ring remained perfect and unbroken for the space of two min* ntes. The next annular eclipse which will be visible to any considerable portion of the Uni- ted States, will take place Sept. 18th, 1838. From the most elaborate calculations, compar* ed with a long series of observations, the length of the Moon's shadow in eclipses, and her dis* tance from the Sun at the same time, vary with- . in the limits of the following table : ^ FSftt4 in either ot tne ocner cases, ine saroe cinnimswnceB.occurnnK w mriviv, r^-f rrji"-- the appearance of the Sun J Why dow not the Moon, in this «i«e, muw » ^SL?? JSK JVfiendid the only eclipse qfthU kind, evervittblein «H^'L"*^>®*€rK;iS2u7i2?^ lour dm tfie ltaninou9Ting,iaongU» path, »-hW% the Uoon^e ehadow varfu in edijnee? What i» the difference between theae two limits ? Whax are the Itmiiettffter distances frotn the' Earth J What is the difference between them? Wiiat is the greatest brcadtb of any spot on the Earth's surmoe, to which a central eclitwo of the Sun can be total 7 What b the breadth oftheg reateet space over which the Sun can be more or less partially eclli sed? Is the penumbra iff the Moon at the Earth's surface in eclipses always cii ett!ar 7 In whai elrew9Manees will the shadow be projected obliquely over the Earth's stiiface? Must the 'hatUna reach the Earth, to produce a partial eclipse ? What is the great- tm^Sf^f? wK^fliffiffaf *** Sun and Moon, within which such a resist wiU !l?^tf?fcti . i?Lii?^^i!** ®V" <»l«P«'.d at the timeof eveiy new Moon, snd the Mooa .. .i«^ ibB I ^B^ cmauartaness WiU an edipse of the fiuiv and to wS^ CCLtMUv wio If the Moon be exactly m one uf her nodes at the time of her change, the Sun will be centrally eclipsed. If she be 1.}® from her node at the time of her change, the Sun 19111 appear at the equator to be about 11 digits eclipsed. If she be 3° from her node at the time of her change, the Sun will be 10 digits eclipsed, and soon ; a digit being the twelfth part of the Sun's diameter. But when the Moon is about 18^ from her node, she will just touch the outer edge of the Sun, at the time of her change, without producing any eclipse. These are called the ecliptic limits. Between these limits, an eclipse is doubtful, and requires a more exact calcula- tion. ' The mean ecliptic limit fur the Sun \n 164° on each side of the node ; the mean ecliptic limit for the Mooq is 10|° on each side of the node. In the former case, then, tliere are 33<^ about each node, making, in all, 66° out of 360°, in which eclipses of the 9vm may happen : in the latter case, there are 21° about each nodoymalcing. in all, 42° out of 360° in which ecliftses of the Moon usually occuiy Tiie proportion of the solar, to the lunar eclipses, therefore, is as 66 to 43; or as il to 7. Yet, there are more Tisibie eclipses of the Moon, at any given place, than of the Sun ; because a lunar eclipse is visible to a wiiolc hemisphere, a solar eclipse only to a small portion of it. The greatest possible duration of the annular appearance of a solar eclipse, is 12 minutes and 24 seconds ; and the greatest possible time during which the Sun can be totally eclipsed, to any part of the world, is 7 minutes and 58 seconds. The Moon may continue totally eclipsed for one hour and three quarters. Eclipses of the Sun always be^in on his western edge, and end on his eastern ; but all eclipses of the Moon com* mence on her eastern edge, and end on her western. If the Moon, at the time of her opposition, be exactly in her node, she will pass through the centre of the Earth's shadow, and be totally eclipsed. If, at the time of her opposition, she be within 6^ of her node, she will still pass through ihe Earth's shadow, though not centrally, and be totally eclipsed : but if she be 12^ from her node, she will only just touch the Earth's shadow, and pass it without being eclipsed. The duration of lunar eclipses, therefore, depends upon the difference between the diameter of the Moon and that section of the Earth's shadtow In what circumstances a the Sun oentrallr edipRed ? What is the ratio between the Moon's distance from her node, and tlie number of dibits that the Sun is eclipsed 7 What tre these limits called l Will there always be eclipses when the Moon is within these limitsl Wfuu i0 the ecltptfe limit for the iSun 7 What is it for the Moon? What number qf degrees, then, are there about eaeh node, and hoio many ota ofWV*, in which soUir eclipses can happen 7 Hoio many in tohich lunar eclipses uoually hap' pen 7 What then is the proportion f^f the solar to the lunar eclipses 7 Why then ar& there more eclipses of the Moon visible at any given place than of the Sun 7 What is the greatest posstbie duration of the annular appearance of a solar eclipse? WItat is the greatest i^ossible duration of a total solar eclipse to any port of the world ? What is the greatest duration of a total lunar eclipse ? On which side of the Sun do solar ocipees always beffin, and on which do they end ) On which side of the Moon do lunar eciip*BS always begin, and on which do tljcy end ) In what drcumstanajs w tiie Moon totaUf ecUpsed ? Beyond what distance from her node, if she be, wUl she only toudh U»e ^rth a shadow, and iwt be ecUpied ? On what then does the dMrationqf lunar eclipses depend! EOUFBBSi fbroofh which she p&Mes. When «d eclipse of the Noon ia both tocai and eentnu, itc duration in the longest possible, amountinit nearly to 4 hoiira* tut the duration of all ecllpaea not centra] varies with her distance Irom fhenode. ECLIPSES OF THE MOON. Fig. 18. K'^W^l The diameter of the Earth's shadow, at the distance of the Mood, is Dearly three times as large as the diameter of the Moon ; aod the length of the Earth's shadow is u early four times as great as the distance of the Moon; exceeding it in the same ratio that the diameter of the Earth does the diame- ter of the Moon, which is as 3.663 to 1. The leo|[lh of the Earth's shadow, and its diameter at the distance of the Moon, are subject to the variations •jcbibited Hi the following tabic. Diameter of the shadow. Lenji^h ol the shad- ow in ma. Sun at the perigee 0ira at his mean distance Sun at the apogee C Moon at the apogee ^ Moon at her wean distance ( Moon at the perigee SMoon at the apogee Moon at her mean distance Moon at the perigee C Moon at the apogee < Moon at her mean distance ( Moon at the perigee 6,232 5.762 6,292 5,270 5,799 6,329 5.306 5,836 6,365 842,217 856,697 871,263 The first colnron of fignres expresses the diameter of the Earth's shadow at the Moon : and as the diameter of the Moon is only 2162 miles, it is evident that it can always be comprehended^by the shadow, which is more than twice aa broad as the disc of the Moon. .' The time which elapses oetween two successive changes ol tne Moon is called a Lunation^ which, at a mean rate, is about 29j- days. If 12 lunar months were exactly equal to the 12 solar months, the Moon's nodes would always occupy the same points in the ecliptic, and all eclipses would happen in the same months of the year, as is the case with the transits of Mercury and Venus : but, in 12 lunations, or lunar months, there are only 354 days ; and in this time the Moon has passed through both her nodes, bt xohat eireumatanees fa the duration of the lunar eclipse the longeat possiblel Whfftia thetength of the greatest duration tf a lunar eclipse 7 With what does the enraticn t^ecVvses, not central, vary J What is the dinmeter of the Earth's shadow at the distance of the Moon ? What is the length of the Earth's shadow ? What is their mtio to each other t Between what HmUa does the length of the Earth's snadote, and Us djatneter at the distance qfthe Moon, vary 7 What is the breadth of the Earth** atodow compared with that cf the disc qfihe Moon 7 What is a lunaUon J How many jg?» do« a lunation embrace ? M hy do not all.ecUpses happen in the some montla <»r BCLIPSfiS. 221 bai has not quite acconipUshed her revolution arrund the Sun : the consequence is, that the Moon^s nodes fall back in the ecliptic at the rate of about 19^^ annually ; so that the eclipses happen sooner every year by about 19 days. As the Moon passes from one of her nodes to the other in 173 days, there is just this period between two succes- sive eclipses of the Sun, or of the Moon, in whatever time of the year, then, we have eclipses at either node, we may be sure that in 173 days afterwards, we shall have eclipses at the other node. As the Moon's nXxleB fall back, or retrograde in the eeliptic, at the rate of 19|o every^ year, they will complete a backward revolution entirely around the ecliptic to tlie same point again, hi 18 years, 225 days ; in which time there would always be a regular period of eclipses, if any complete number of lunations were finished without a remainder. But tnis never happens ; for if both the Sun and Moon should start from a line of conjunction with either of the nodes in anypoint of the ecliptic, the dun would perform 18 annual revolutions and 222^ of another, while the Moon would perforo v^ lunations, and 85° of another, before the jiode would come aroimd to the same point of the ecliptic acain : so that the Sun would then be 138° from the node, and the Moon 85° froiii the Sun. But afler 223 lunations, or 18 years. II days,* 7 hours, 42 minutes, and 31 seconils, the Sun, Moon, and Elarth, will return so nearly iu the same position wiih respect to each other, that there will be a regular return of the »am» edipscsfor many ages. This ffrand period was discovered by the Chaldeans, and by them railed Saros. It, therefore, to the mean time of any eclipse, either of the 8un or Moon, we add the Chaldean period of Is vears and 11 days, we shall have the return of the same eclipse. This mode of predict* in« eclip>:es will hold good for a thousand years. In this period there are usually 70 eclipses ; 41 of the Sun, and 29 of the Moon. The number of eclipses in any one year, cannot be less than two, nor more than seven. In the former case, they will both be of the Sun ; and in the latter, there will be five of the Sun, and two of the Moon — those of the Moon will be total. There are sometimes six ; but the usual number ia four: two of the Sun, and two of the Moon. The cause of this variety is thus accounted for. Although the Sun nsaally passes by both nodes only once in a year, he may pass the same node again a little before the end of the year. In consequence of the r^rograde motion * If there are/our leap yean in this Interval, add 11 day* ; but if there are Jive, add only ten days. How fax do the Moon's nodes fall back in the ecliptic anmially, and how much looner do the eclipses happen every vear 9 In what time doea the Moon pass from one of her aodes to tlie otlier 1 What is the length of the time winch elapses betweoa two siicceswre «dipses of the Sun or the Moon ? After there have been eclipses at one node, in what lime may we be sure that there will be eclipses at the other 7 in what time do the Moon*e nodeg complefe a backward revolution around the ecliptic 7 Why i» there noi aXtoayt 1 re^iUar period of eclipeee in thU time 1 If the Sun and Moon ehould both etart from a line ef conjunction with either node, how many reoolutiona v?ould the Sun terform, and how many lunatione the Moon, before the node would come around to he same point again ? After how many lunation* will the Sun^ Moon, and Earthy etum so nearly to the same position with respect to each other, that there will be « regular return qfthe same eclipses for many ages J What nation discovered tMs grand period, and what did they call it 7 What is the mode of predicting eclipses, tctth which this fact fumiOus us 7 How many eclipses are there usually in this po- rted 7 What is the least, and what the greatest number of eclipses, in any «» JC"' 3 the former case, what eclipses will they Be? What, in the latter? What » «» ««J camber of eclipses in the year, and what eclipses are they I Pleaae iaeplain the cause qr this variety, 19* of the Moon'a nodea, he will come to either of them 173 days after paweof the other. lie mar, therefore, return to the fame node In about 346 daja, having ihua paasecf one node iteice and the other tmcey making each lime, at each, an eclipse of both the Bun and the Mood, or, six in alL And, siuce 12 lunationa, or X4 days from the ^nt eclipse in the beginning of ihc year, leave room for another new Moon before the close of tlie vear, and ainco this new Moon may fall within tlie ecliptic limit, it is possible for the dtm to be eclipsed again. Thus there may be seven eclipses in tlic same year. Again: when the Moon ciianges in either of her nodes, she cannot come witliin the lunar ecliptic limit at the next full, (though if ahe be full In one of her noiles, she may come into the solar ecliptic limit at her next change^j and six months afterwards, she will change near the oiber node ; thus mak- iBgonly two eclipses. • The following is a list of all the solar eclipses that will be visible in Europe and America during the remainder of the present century. To those which will be visible in New-England, the number of digits is annexed. Year. Month Day & hour. Digits Year. Month Day and Hour. Digits 1834, Nov. 30 1 22 P. M. \W> 1869, Aug. 7 5 21 A. M. lOi IRXi, May 15 7 25 A. M. 81 1870, Dec. 22 6 A. M. 1R3«, Sept July 18 3 27 P. M. 11 1873, May 26 3 A. M. 1841, 18 10 A. M. 1874, Oct. 10 4 A. M. 1812, July 8 Mer. 1875^ Sept. 29 5 56 A. M. ^^ 1814, Uec. 9 3 46 P. M. 2m 1876, Mar. JB 4 11 P. M. 3| 1815, May 6 4 55 A. M. 4* 1878, July 29 4 56 P. M. 71 1316, Apr. 25 II 15 A. M. v% 1879, July 19 2 A. M. 1847^ Oct. 9 1 A. M. 1880, Dec. 31 7 30 A. M, H 184a Mar. 6 7 50 A. M. 6i 1882, May 17 I A. M. 1851^ July 28 7 48 A. M. 3 1885, Mar. 16 36 A. M. ^ 1851 May 96 4 26 P. M. 11 1836, Aug. 29 6 30 A. M. 186R Mar. 15 6 14 A. M. 1 1887, Aug. 18 10 P. M. » 1839, July 29 5 32 P. M. 2 1890, June 17 3 A. M. 1860. July 18 7 23 A. M. 6 1891, June 6 Mer. 1861, Dec. 31 7 30 A. M. H 1892, Oct. 20 19 P. M. 8^ I86», May 17 1 OP. M. 1895, Mar. 26 4 U A. M. 1860, Oct. 19 9 10 A. M. 31 1896, Aug. 9 OMer. 1866, Oct. 8 11 12 A. M 0" 1897, July 29 9 8 A. M. H 1867, Mar. 6 3 A. M 1899, June 8 OMer. m 1868, Feb. i 23 10 A. M. 1900, May 28 8 9 A. M. u The eclipses of 1838, 1854, 18G9, 1876, and 1900, will be very lai^e. Id thoM of 1846, 1858, 1861, 1373, 1875, and 1880, the Sun will rise eclipsed. In that of 1844, the Sun will set ecHpsed, Those of 1838, 1854, and 1875^ irOI be annular. The scholar can continue this table, or extend it baekwwrdiri^ bv adding or subtracting the Chaldean period of 18 years, 11 days, 7 houn^ M minutes, and 31 seronds. MARS. ^ Mars is the first of the exterior planets, its orbit lying immediately without, or beyond^ that of the Earth, while those of Mercury an5 Venus are within. Mars appears to the naked eye, of a fine ruddy com- plexion ; resembling, in colour, and apparent magnitude, the star Antares, or Aldebaran, near which it frequently passes. It exhibits its greatest brilliancy about the time ' 1 ■■ ■■ ■- What It thfP02»tiooof Man in the s^ s^tem 7 DeMsibe its appearanee to tlie na- KM ape. WbndoesiiaxhftititigreataBtlniUfaDejrl MAXUk £13 that It rises when the Sun sets, and sets when the Sun rises; because it is then nearest the Earth. It is least brilliant when it rises and sets with the Suq ; for then it is Gve times farther removed from us than in the former case. Its distance from the Earth at its nearest approach is about 50 millions of miles. Its greatest distance from us is about 240 millions of miles. In the former case, it appears nearly 25 times larger than in the latter. When it rises before the Sun, it is our morning star ; when it sets aftei the Sun, it is our evening star. The distance of all the planets from the Earth, whether they be Interior or' exterior planets, varies within the limits of the diauneters of their orbits; for when a planet is in that point of its orbit which is nearest the Ec:th, it is evidently nearer by the whole diameter of its orbit, than when it is in the opposite pointy on the other side of its orbit. The apparent diameter of the planet will also vary for the same reason, and to the same degree. Mars is sometimes seen in opposition to the Sun, and sometimes in superior conjunction with him ; sometimes gibbous, but never horned. In conjunction, it is never, seen to pass over the Sun's disc, like Mercury and Venus. This pruves not only that its orbit is exterior to the Earth's orbit, but that it is an opaque body, shining only by the re* flection of the Sun. The motion of Mars through the constellations of the zodiac is but litjie more than half as great as that of the Earth ; it being generally about 57 days in passing over one sign, which is at the rate of a little more than half a decree each day. Thus, if we know what constellation Mars enters to day, we may conclude that two months hence it will he in the next constellation ; four months hence, in the next ; six months, in the next, and so on. Mars performs his revolution around the Sun in 1 year and 10^ months, at the distance of 145 millions of miles; moving in its orbit at the mean rate of 55 thousand miles an hour. Its diurnal rotation on its axis is performed in 24 hours, 39 minutes, and 21^ seconds; which makes its day about 44 minutes longer than ours. Why is it most brillinnt at this time ? What are its least and greatest distances firom i» ? How much larger does it appear in the fiM'mer case than in the latter ? IVfthtn what limi s does the dUtance of all the planets from the Earth vary 7 With tohat doe^ the apparent diameter of a planet vary 7 What moon-like phases bat Mars ) What does the &ct, that it never assumes the crescent form at its conjunctioni p^ve, in regard to its situation ? How do we know it to be opaqae 7 What is the rat« of its motion through the constellations of the xodiae, compared with thnt of ttie Carth I How long is it in passing over one sign ? At what rate per day is this ? How. then, if wa know in what constellation it is at any one lime, may we determine in what oonstellatioii It will be at any subsequent time 7 In what time does it periorm its revolution around tha Sun 7 What is its diatanco from the Sun 7 What is the mean r^«i of its motion in its or* bit per hour 7 In what time docs it perform its revolutkio on its axis ? What* tlicni is Htm length of its day. compared with that of the £arth I 324 MAKa Its mean sidereat rorolutloo Is performed In 686.9796458 solar days; or fn C% (lays, 23 hours, 30 minutes, 41.4 seconds. Its aynndieal revolution is nerformed in 779.996 solar days ; or in 779 days, 22 hours, 27 minates, and pO seconds. Its form is that of an oblate spheroid, whose polar diame- ter is to its equatorial, as 15 is to 16, nearly. Its mean i2iameter is 4222 miles. Its bulk, therefore, is 7 times less than that of the Earth ; and being 50 millions of miles farther from the Sun, it receives from him only half as much light and heat. The inclination of its axis to the plane of its orbit, is about 2S}^. Consequently, its seasons must be very similar to those of the Earth. Indeed, the analogy between Mars and the Earth is greater than the analogy between the Earth and any other planet of the solar system. Their diurnal motion, and of course the length of their days and nights, are nearly the same ; the obliquity of their ecliptics, on which the seasons depend, are not very different ; and, of all the superior planets, the distance of Mars from the Sun is by far the nearest to tnat of the Earth ; nor is the length of its year greatly different from ours, when compared with the years of Jupiter, Saturn, and Herschel. To a spectator on this planet, the Earth will appear al- ternately, as a morning and evening star; and will exhibit all the phases of the Moon, just as Mercury and Venus do to us ; and sometimes, like them, will appear to pass over the Sun's disc like a dark round.spot. Our Moon will never appear more than a quarter of a degree from the Earth, although her distance from it is 240,000 miles. If Mars be attended by a satellite, it is too small to be seen by the most powerful telescopes. When it Is considered that Vesta, the smallest of the asteroids, which is once and a half times the distance of Mars from us, and only 269 miles in diameter, is perceivable in the open space, and that without the presence of a more conspicuous body to point it out, we may reasonably conclude ttiat Mars is without a moon. The progress of Mars in the heavens, and indeed of all the superior pla- nets, will, like Mercury and Venus, sometimes appear direct, sometimes retrograde, and sometimes he will seem stationary. When a superior f>lanct first becomes visible in the morning, wesi of the Sim, a little a(ler» rs conjunction, its motion is direct^ and also most rapid. Wticn it is first seen east of the Sun, in the evening, soon ader its opposition, its motion is retrograde. These retrograde movements and stations, as they appear to a Jn what time doe* it perform itt mean sidereal revolution 1 In what time, ite «y^ nodical revolution 1 What are its fomi and ilimensions ? What, then, is its bulk, com- pared with the Earth's, and how much less light and heat does it receive from the 9nn I Wliat IS the inclination of iti axis to the plane of its ortrit J How are its seasons, oompa- fed with those ot the Earth ) In what particulars is there a greater analogy beiweoa Mars and the Larth, than between the Earth and any other planet in the solar system ? What must be tlw appearance oHhe Earth to a spectator at Mars ? What is the gieatest dia- tarKMfrom the Eartli at which our Moon will appear to him to be? »%y may we rem- M««6/y conclvde that Mare has no eaiellUe f Detcrtbe tk" vrogreee ^Mare through IT frdm [lie Earlh, ii ' jfilie Caperi 1 eyjteit lo Bll llie 1 MU, uc The telescopic phenomena or Mars afford peculinr in- terest to aswonomers. They behold its disc diversified with numerous Irregularand vaiiable spot<=, and ornamented with zones aad belts of varying hrilliancy, that form, and disapfiear, by turns. Zones of intense brightness aie 1o be seen in its polar regions, subject, however, to gradual changes. That of the southern pole is much the most bril- liant. Dr. Herschel supposes that they are produced by the reflection of the Sun's light from the frozen regions, and that the melting of these masses of polar ice is the cause of :he variation in their magnitude and appearance. He was the more confirmed in these opinions hy observ- ing, that after the exposure of the luminous zone about the north pole to a summer of eight months, it was considerably decreased, while thai on the south pole, which had been in total darkness during eight months, had considerably in- creased. He observed, farther, that when this spot was most lo- ininous, the disc of Mars did not appear exactly round, and that the bright part of its southern limb seemed to be swollea or arched out beyond the proper curve. The extraordinary height and density of the atmospbere of Mars, are supposed to be the cause of the remarkable redness of its light. It has been found by experinaent, that when a beam of white light passes through any colourless transparent me- dium, it§ colour inclines to red, in proportion to the density of the medium, and the space through which it ha^ travellecl. Thus the Sun, Moon, and stars, appear of a reddish colour 286 TB ASTCROlDdk when near the horizon; and everjr luminous object, seen throufi^h a mist, is of a ruddy hue. This phenomenon may be thas explained . — The momentum of the red, or least refrangible rays, being greater than that of the viotct, or most rcfran* gihie rays, the former will make their way through the resisting uiccliuiii, whik: the latter are either reflected or absorbed. Tlic colour of the f/earn, therefore, when it reaches Ihe eye, must partake of the colour of the least refrangible rays, and this colour must increase with the distance. The dim light, therefore, by which Mars is illuminated, having to pass twice through its atmosphere before it reaches the Earth, must l>c deprived of a great pro- portion of its violet rays, and consequently then be red. Dr. Brewster wip- goscs that the difTcrence of colour among the other planets, and even the xed stars, i$ owing to the different heights and densities of their atinos* pheres. stars, 1$ THE ASTEROIDS, OR TELESCOPIC PLANETS. Ascending higher in the solar system, we find, between the orbits of Mars and Jupiter, a cluster of four small plan- ets, which present a variety of anomalies that distinguish them from all the older planets of the system. Their names are Vesta^ Juno, Ceres, and Pallas, They were all dis- covered about the beginning of the present century. The dates of their discovery, and the names of their discoverers, are as follows : Ceres, January 1, IPOl, by M. Piazn, of Palermo. Pallas, March 28, 1802. by M. Olbers, of Bremen. Juno, September I, 1304, by M. Harding, of Bremen. Vesta, March 29, 1807, by M. Olbers, of Bremen. The scientific Bode* entertained the opinion, that the plane- tary distances, above Mercury, formed a geometrical series, each exterior orbit being double the distance of its next interior one, from the Sun ; a fact which obtains with re- markable exactness between Jupiter, Saturn, and Herschel. But this law seemed to be interrupted between Mars and Jupiter. Hence he inferred, that there was a planet want- ing in that interval ; which is now happily supplied by the discovery of the four star-form planets, occupying the very space where the unexplained vacancy, presented a strong objection to his theory. * Accordinj; to him, the distances of the planets may be expressed nearly as foiknrs : the Earth's dixtance from tlic Sun being 10. Mercury 4 -=» 4 Venus 4-1-3X1 - 7 The Earth 4+3x2 - 10 Asteroids 4-4*3X2» — 28 Jupiter 4-4-3X2' - 52 Saturn 4-^-3x25 — 100 Mars 4-1-3X2* - 16 Herschel 4-f 3X2^ - 196 Comparing these values with the actual mean distances of the planets m>m the Son, wa cannot but remark the near agreement, and can scarcely hesitate to pronotmce that Uie respective distances of the planets from the Sun. were assigned according to a Ikw, althuucrh we are entirely ignorant of the exact law, ana of the reason for that law.— £rinl9> let/'tt Blement8, p. S9. What new planets have been discovered within the present century? Where are tbey situated ? What are the dates qf their diseoverii, ana the natnet <{/ their diacovereat why did Bode infer that thetc was a planet wanting between Man and JupUer* rac ABTEBOioa. 897 These bodies are much smalier in size than the older planets — they all revolve at nearly the same distances from the Sun, and perform their revolutions in nearly the same periods, — their orbits are much more eccentric, and have a much greater inclination to the ecliptic, — and vi^hat is altogether singular, except in the case of comets — all cross each other; so that there is even a possiinliiy that two of these bodies, may, some time, in the course of their revolu- tions, come into collision. The orbit of Vesta is so eccentric, that she is sometimes farther from the Sun than either Ceres, Pallas, or Juno, although her mean distance is many millions of miles less than theirs. The orbit of Vesta crosses the orbits of all the other three, in two opposite points. 7%e student should here refer to the Figures^ Plate L of the Atlas, and veri- fp suck of these particulars as are tiiere represented. ^ It would he well for the teacher to require him to observe jiarticularly the positions qf t-heir orbits^ From these and other circumstances, many eminent as- tronomers are of opinion, that these four planets are the fragments of a large celestial body which once revolved between Mars and Jupiter, and which burst asunder by some tremendous convulsion, or some external violence. The discovery of Ceres by Piazzi, on the first day of the present century, drew the attention of all the astronomers of the age to that region of the sky, and every inch of it was minutely explored. The consequence was, that, in the year following. Dr. Olbers, of Bremen, announced to the world the discovery of Pallas, situated not many degrees from Ceres, and very much resembling it in size. From this discovery. Dr. Olbers first conceived the idea that these bodies might be the fragments of a former world 5 and if so, that other portions of it might be found either in the same neighbourhood, or else, having diverged from the same point, *'they ought to have two common points of reunion^or two nodes in opposite regions of the heavens through which all the planetary fragments must sooner or later pass." One of these tiodes he found to be, in the constellation Virgo, and the opposite one, in the Whale ; and it is a re- matkable coincidence that it was in the neighbourhood of In what paiticulan do these new planets differ from the older planets 7 How is ft pos* ■ibWthat two of them slioult] over eome into collision 1 How is it that Vesta is sometimes &rthcr from the Sun thaneiUwr Ceres, Pallas, or Juno, when her mean di^itaiice is manv intUions of miles less tlutn tiieirs } What is ttie position of her orbit with regard to tlieur oitiits 7 What theory in regard to the origin of thae planets have some astronomers de- lived iirom these and some other drcmnstances 7 who first conceived this idea 7 How eune be to have this idea 7 Where did he imagine otharfiraginflnti might be found} Ui wbiit eonstellatiflM dU he findtbeee oodei to bej f28 TH£ A«T6B0tlM. the latter constellation that Mr. Harding discorered the planet Juno. In order therefore to detect the remaining iragments, if any existed, Dr. Olbers examined, three times every year, all the small stars in Virgo, and the Whale; and it was actually in the constellation Virgo, that he dis- covered the planet Vesta. Some astronomers think it not unlikely that other fragments of a similar description may hereafter be discovered. Dt. Brewster attributes the fall of meteoric stones to the smaller fragments of these bodies happening to come within the sphere of the Earth's at- traction.' Meteoric stones, or what are generally termed aerolites, are stones which sometimes fall from the upper regions of the atmosphere, upon the Earth. Tlie substance of wiiich they are composed, is, for the most part, metallic; but the ore of whicli it consists is not to be fnimd in the same constituent fnoporlions in any known substance upon the Earth. Their fall is general- y preceded bv a luniinous appearance, a hissing noise, and a loud explo- sion ; and, wnen found immediately after their descent, they arc always hot, and usually covered with a black crust, indicating a state of exterior fusion. Their size varies from that of small fragments of inconsiderable weight, to that of the most ponderous masses. They have been found (o weigh from 300 poun(ts to several tons; and they have descended to the Earai villi a force sufficient to bury liiem many feet under the surface. Some have supposed that they arc projected from volcanoes in the Moon ; others, ihat they proceed from volcanoes on the Earth ; while others iinajsine that they are generated in the r^iuns of the atmosphere ; bat the truth, probably, is not yet ascertained. ~ In some instances, these stoYies have penetrated through the roofs of houses, and proved destructive to the inliabitanls. If we carefully compute the force of gravity in the Moon, we shall findf that if a body were projected from her surface with a momentum that would cause it to move at the rate of 8,200 feet in the first second of time, and in the direction of a line joining the centres of the Earth and Moon, it would not fait ajjralu to the surface of the Moon ; but would become a sa- tellite to the Elarth. Such an impulse might, indeed, cause it, even after many revolutions, to fall to the Earth. The fall, therefore, of these stones, from the air, may be accounted for in this manner. Mr. Ilarto calculates, that even a velocity of 6000 feet in a second, would be sufficient to carry a body projected from the surface of the Moon beyond the power of her attraction. If so, a projectile force three times greater than that of a cannon, would carry a body from the Moon beyond the point of equal attraction, and cause it to reach the Earth. A force equal to this is often exerted by our volcanoes, and by subterranean steam. Hence, there is no impossibility in the supposition of their coming from the Moon ; hut yet I think the theory of aerial coosolidation the more plausible. Vesta appears, however, like a star of the 5th or 6th magnitude, shining with a pure steady radiance, aird is the only one of the asteroids which can be discerned by the naked eye. Wlwre were Juno and Vesta act nally fimnd ? Howdid Or. Olbera discover Vesta 9 To wluU docs Dr. Brewster attribute the mil of meteoric stones 7 What is meant by thm expr»isifm, meteoric stones ? Qfwhat substance are they ccm/posed t In what r^ sped do they differ frvfn any metallic substances knoton on the Earth 7 What cations generuJiy precede their fall 7 In teluu state are they found to be after their descen t7 tVhat is their magnitude 7 What theories have been adopted to account for their origin 7. Explain how it is not impossible that they may come fttm tim Moon. Describe the appearance a* Veata» JcHO, the next planet in order after Testa, reTolrea BTound the Sun in A years, 4^[iiomh9, at the mean dtstauce of 254 millioDs of miles, morinj^ in her orbit at the rale of 41 thousand miles an hoar, fifer diameter is estimated at 1393 miles. This would make her magnilude 183 times less than th^ Earth's. The light and heat which she receives from the Sun is seven limes less than that received by the Earth. The eccentricity of her otbit is so great, that her great- est distance from the Sun is nearly double her least distance; ao ihat, when she is in her peHkelion, she is nearer the Sun by 130 milliocis of miles, than nhen she ia in her apkelioTt. This great eccentricity has a corresponding effect upon her rate of motion ; for being so much nearer, and there- fore 90 much more powerfully atlracted by the Sun at one time than at another, she moves through that half of her orbit which is nearest the Sun, in one half of the time that she occupies in completing the other half. According tn Bchracter, the diuneter of Juno li 14!e mao; ind ilis ii pi.'neu" SchtDEi^i ■Sri-e™lSi''"h.i'lh8 7»riMloii in Sir brllUarcrli uine Mine lie ihinka ii nnt jmproliabJe thftl UieH changes maj ariaa from Cebes, the planet next ia order afier Judo, rerolves about the Sun in 4 years, 7^ months, at the mean distance of 263)' millions of milfs, moving in her orbit at the rale of 41 ihousand miles an hour. Her diameter is estimated at 1583 miles, which makes her magnitude 1S5 times less than the Earth's. The intensity of tbe li^hi and heat which she re- ceives from the Sun, is about 7^ times less than that of thoae received by the Earth. Ceres sbines with a ruddy colour, and appears to be only about the size of a star of the 8lh maguilude. Consequent- ly she is never seon by the naked eye. She is surrounded by a species of cloudy or nebulous light, which gives hei somewhat the appeSTanee of a comet, fonniog, accordiiig (o Schroeier, an atmosphere 675 miles in beig^hi. Ihe from it, is 27 times less than that received by the Earth. When Jupiter is in conjunction, he rises, sets, and comes to the meridiao with the Sun ; but is never observed to malie a transit, or pass over th« Sun's disc; when in opposition, he rises when the Sun sets, sets when the Son rises, and comes to the meridian at midnight, which never happens in the case of an interior planet. This proves that Jupiter revolves in an orbit which is exterior to that of the Earth. As the variety in the seasons of a planet, and in the length of its days and nights, depends upon the inclination of its axis to the plane of its orbit, and as the axis of Jupiter has no inclination, there can be no difference in his seasons, on the same parallels of latitude, nor any variation in the length of his days and. nights. It is not to be understood, however, that one uniform season prevails from his equator to his poles ; but that the sam^ parallels of latitude on each side of his equator, uniformly enjoy the same season, what* ever season it may be. About his equatorial regions there is perpetual summer ; and at his poles everlasting winter ; but yet equal day and e^ual night at each. This arrangement seems to have' been kindly ordered by the beneficent Creator ; for had his axis been inclined to his orbit, like that of the Earth, his polar winters would have been alternately a dreadful night of si^ year s darkness, Wfiat U the, difference between his polar and eQuatoriel diantetera? What dott fii« fbrm appear to he^ through a good telescope? What it the direction ef hie longer diameter ? At what rate per nour are his equatorial inhalNtants rarried br bis Biotion on hifl axis 1 How much Arther is tUs than the equatorial inhabitants of tlie Earth are carried in 24 hoanl What is Jupiter's teue mean diameter? How much (peater is it than the Earth's 7 What is his Toimne, compared with the Earth's ? What IS the degree of lieht and heat which he receives from the sun, compared with that re> ceived by the Eartli 1 How do toe know that Jupiter^* orbit is exterior to that of the Earth? What is the anangement of Jupiter's seasons, and of his days and nigfatal Bad ius axis been inclined to the pbueorfaii oiiiit.like that ofoor Earth, how loot wwU s polar nights have been ? iOPtTCR* SS3 ItSLESCO^IC APPEARANCES OF JUPITER. Fig. 17. Jupiter when viewed through a telescope, appears to be surrounded by a number of luminous zones, usually termed belts, that frequently extend quite around him. These belts are parallel not only to each other, but, in general, to his equator, which is also nearly parallel to the ecliptic. They are subject, however, to considerable variation, both in breadth and number. Sometimes eight have been seen at once; sometimes only one, but more usually three. Dr. Herschel once perceived his whole disc covered with small belts. Sometimes these belts continue for months at a time with little or no variation, and sometimes a new belt has been seen to form in a few hours. Sometimes they are interrupted in their length ; and at other times, they appear to spread in width, and run into each other, until their breadth exceeds 5,000 miles. Bright and dark spots are also frequently to be seen in the belts, which usually disappear with the belts themselves, though not always, for Cassini observed that one occupied the same position more than 40 years. Of the cause of these variable appearances, but little is known. They are generally supposed to be nothing more than atmospherical phenomena, resulting from, or combined with, the rapid mo- tion of the planet upon its axis. Different opinions have been entertained by astronomers respecting the ;y have been regardea i or as openings in the aluiosphere of the planet, while others itnagine that cause of these belts and spots. By some they have been regardea as cloudSy they are of a more permanent nature, and are the marks of great physical revolutions, which are perpetually agitatiajr and changring the surface of the planet. The first or these opinions sufficiently explains the variations In the form and magnitude of the apota, and the paralUUsm of the belti. The spat first observed by Cassini, ki 1665, which has both disappeared and-re-appcared in the same form and position for the space of 43 years, could not possibly he occasioned by any atmospherical variations, but seems evidently to be connected with the surface of the planet. The form of the ■■■■■I ■» ■■ -..—-I ■[■■■■■II ■■■-■■■ ■■■ ^>— — ^w^ Describe Japiter't appeanoce, as seen throuffh a telescope. What is supposed to be the cause of these phenomena 7 Relate wme qf the different optnione entertained bff %*tronomer§ on thia sitbjeot. 20* 1SS4 rofmiu belt, aecordmg to sotne astronomers, may be accounted lor by «d|>poilBf Chat the atmosphere rellects more light than the body of the planet, and thai the clouds which float in it, being thrown into parallel atraia br the rafiklity of its diurnal niotion, Ibrni regular intersfices, through which are «ee*i its opaque body, or any of the permanent spots which may come within ihe range of the opening. Jupiter is also attended by four satellites or moons, some of which are visible to him every hour of the night; exhib- iting, on a small scale and in short periods, most of the phe- nomena of the solar system. When viewed through a tele- scope, these satellites present a most interesting and beau- tiful appearance. The first satellite, or that nearest the planet, is 259,000 miles distant from its centre, and revolves around it in 42^ hours ; and appears, at the surface of Jup*- ter, four limes larger than our Moon does to us. His second satellite, being both smaller and farther distant, appears about the size of ours; the third, somewhat less; and the fourth^ which is more than a million of miles from him, and takes 161 days to revolve around him, appears only about one third the diameter of our Moon. These satellites suffer frequent eclipses from passing through Jupiter^s shadow, in the same manner as our. Moon is eclipsed in passing through ibe Earth's shadow. The three nearest satellites fall into his shadow, and are eclips- ed, in every revolution; but the orbit of the fourth is so much inclined, that it passes by its opposition to him, two years in six, without falling into his snadoiv. By means of these eclipses, astronomers have not only discovered that light is 8 min«l€s and 13 seconds in coming to us from the Sun, but are also enabled to determine the longitude of pla- ces on the Earth with greater facility and exactness than by any other methods yet known. It was long since foiMid, by the most car«ful observationfi, timt when th« Earth is in ihat part of hor orbit which is nearest to Jupiter, the eclipses appear to happen 8^ 13''' aoontr than the taMes predict; and when in Ihat part of her orbit which is farthest from him, 8' 13^' hUer than the tal)les predict ; nmliing a total difference in lime, of IG' 26'^ From the moan of 60JO eclipses observed by Delambre, this disagreement between 'Observation and calculation^ was satisfactorily settled at 8' 13"^, while both •were con8■^«[ered equally; ■o«rrect. Now when tl>e eclijxses happea sooner than il>e tables, Jupiter »s at his -nearest approach to Ihe Kartli — Mfien later, at his greatest distance ; so that the difference in his distances from the Eartii, in the two cases, is the whole diameter of the Earth^s orbit^ or about •190 millions of miles. Ilcnoe, it is -concluded that light is not inst^tnfane- How many satellitefl has Jupiter? How often -are they visible to him ? What is the distance from him of liis first or nearest satellite ? What is the time of its re\'alutKNi } What iM its apparent msfrnitude at the surface of Jupiter, compared with the maimitudo of tne Moon, as -seen oy u« J What ore the apparent magnitudes of his other satelntes* as seen at his surface, compared M-ith that of the Moon as seen at the Earth ? What ia tlK* distanne of his fourth satelHte from him ? What is the time of its rovoiution 7 llow often are his three nearest satellites eclipsed ? How often bis fourth 7 Why is it not eclipsed as often as the others 7 What imprntant purposes have tliese eclipses sle. SateUites. ^irst, Second, Third. Fourth, Revolutioik App. Diam. Mean Dist. Id. 18b. 28m. 3 la 14 7 a 43 16 16 32 1. 667 I. 189 1. 050 0. 560 259,000 414,000' 647,000 l,F64,00O \. Saturn is situated between the orbits of Juptter and Her- schel, and is the most remote planet from the Earth of any that are visible to the naked eye. It^may be easily distin- guished from the fixed stars by its. pale, feeble, and steady light. It resembles the star Fomalhaut, both in colour and size, differing from it only in tlie steadiness and uniformity of its light. From the slowness of its motion in its orbit, the pupil^ throughout the period of his whole life, may trace its appa- reht course among the stars, without any danger of mistake. Having once found when it enters a particular constella- tk>a, he may easily remember where he is ta look for it m any subsequent year ; because, at a mean rate, it is just 2^ years in passing over a single sign of constellation. Saturn's mean daily motion among the stars is only aboat 2^y the thirtieth part of a decree. Saturn entered the constellation Virgo about the beginning of 1833, antt aofllinaed in it until tha middle of tiio^ year 1835^ when he passed into-U- hL what respect are Jupiter^ satellites an epitome of the solar system. 7 What is JupK tor's appearance, as seen from his neaiesfe satellite 7 WHat are the diameterti mean die- tttnae»t and timet of the rewOutiotKif hie satellttee? Where, in the solar system, is Salum situated 1 How may it be distioguiahed from the fixed stars ? W hat star does it sesembie ? In what respects is it like it, and in what is it different from it 7 How may his place among the stars be readily found 1 What is about the rate of hir mean daily mo* Man among the stars 7 When did Saturn enter the coneteilation Virgo, and how long dMhaoorUtnueinitl What otmeteUation did ht wurnextt and how long wlUhi tontimtc in iff 290 MTUBIt. The meao distance of Silura from the Sun is neat]f double that of Ju[ii(«^r, being about. 909 millions of miles. His diametec is about 82,000 miles ; his volume therefore is elerat hundred times greater Ebau the Earth's. Moving; in his orbit al th^ rate of 22,000 miles an hour, he requires 20} years to complete his circuit around the Sun : but bis diurnal rotation on his am is accomplished in 10^ hours. His year, therefore, is nearly thirty limes as long as ours, while his day is shorter by more than one half. His yeai contains about 25,150 of its own days, which arc equal to 10,759 of our davs. The surface of' Saturn, tike thai of Jupiter, is: diversified with belts and dark spots. Dr. Hcrsche! sometimes per- ceived five belts on his surface ; three of which were dark, and two hrtght. The daik belts have a yellowish tinge, and fcnerally cover a broader zone of th« planet than those of iipiter. To the inhabitants of Saturn, the Sun appears 90 times less than he appears to the Earth; and they receive from him only one ninetieth part as much light and beat. But it is computed that even the ninelielk part of the Sun's light exceeds the illuminating power of 3,000 full moons, which would be abundantly sutScient for all the purposes of life. Fits. IB. elescopic appearance ■n is unparalleled. It more interesting than with all his moons :s. That which emir distinguishes this trom every other in em, is 3 magnificetit rpetual light. light of the ring is -illiani than the pla- WkTOtOL W7 net Itself. It turns around its centre of motiod in the same tinie that Saturn turns on its axis. When viewed with a good telescope, it is found to consist of two concentric rings, ivided by a dark band. By the laws of mechanics, it is impossible that the body of the rin|^ should retain its position by the adhesion of the particles alone ; it mast nc* cesaariiy revolve with a velocity that will generate centrifugal force suffi- cient to balance the attraction of Saturn. Observation confirms the truth of these principles, showing that the rings rotate about the planet in 10| hoars^ which is considerably less than the time a satellite wonld take to, re- volve about it at the same distance. Their plane is inclined to the eeliptio in an angle of 31^. In consequence of this obliquity of position, they al- ways appear elliptical to us, but with an eccentricity so variable as to ap* pear, occasionally, like a straight line drawn across the planet; iiv which case thcv are visible only by the aid of superior instruments. Such was their position In April. 1833 ; for the Sun was then passing from their soutk to tbeir north side. The rings intersect the ecliptic m two opposite poiotsb Saturn's rings. Fig. 19. Why fftouU we judge^ prevUmt to tthumutiant that 1h»$s rinft mv$t rtwetm 4tr€nind him 7 Does obgervation eoft^rm thie opinioH 7 In xohai time do the rhun vewttve about the planet 7 U thie a gretuv or lest time than m eaeellite at the tame tf mn $a^ceu>owld require to revolve aboutit 7 Whff do the HnieeUumjfe appear elHpticm aueJ To what extent doee the eeeentrietty^ the rtttge vary 7 WhatUthapoe^ nqf the Tinge vfUhregofdta the eeUftUJ :h mtj tM edled lh«ir nodu. ThMS palnu ue In lonfttodc 170*, lr*r««. Wlien, llienrore, Buiitii is in tiilierorihnD p^ii. hli i '-'-"''"■le iDui. On (lie e«iirai7. when IiIb kmcltiKts i3 3a°,or: i.^ ._ .L u illv»nli«^ As ine sibreiof Iha i lie wFiHi in tlie I The p.«oiiinj[ diagruni nre m t Ttic MkiHine are [he iliiei during iSe enauloKmoluiUwi or iha pluM^ nliFiiilkinein Arl'swilriclaniilludeiaHuctl Ihsllhe rLng>will<)r Ihe EuUl hg raiouniljly Biliialed} cillier bt invi^lc, or )eeB to Itie (ceiiten aJvao. IS33 April. 1 a)° of Virgo. I Inililble. IS»Jeing the largest of all, is seen without much difficulty. Cassini discovered the Ist, 2d, 3d, and 5th satellites, between October, 1671, and Marcti, 1681. Dr. lierschol discovered the 6th and 7th in 1789. These are nearer tu Saturn tlmn any of the rest, tliougli, to avoid confusion, they are named in the order of thei^ discovery. The sixth and seventh are the smallest of the whole ; the first and second are the next smallest; the third is fi^reater than the first and second ; the fourth is the largest of them all ; and the fifth surpasses the rest in brightness. Their respective distances from their primary, vary from half the distance of our Moon, to two millions of miles. Their periodic revolutions vary from 1 day to Tg^^ys. The orbits of the six inner satellites, that is, the^>^f^d, 3d, 4th, 6th, and 7th, all lie in the plane of SaUHrtf^ rings, and revolve around their outer edge; while the 5th satellite de- viates so far from the plane of the rings, as sometimes to be seen through the opening between them and the planet. I^aplace imagines that the accumulation of matter at Saturn's equator ro< tains the orbiis of the first six satellites in the plane of the equator, in the same manner as it retains the rings in that plane. It ha.s been satisfactorily ascertained, that Saturn has a greater accumulation of matter about his *■ This happens, as we liave already shown, when Satum is eitlier in the 20th dcfree of Pisces, or tw* 90th degree of Virga When be is between these points, or in the 'iutfa de- pee either of Gemini or of Sagittarios, liis ring appears ntost open to us, and nuwe in tlw rorai of on oval> whose longest diameter is to tlie shortest as 9 to 4. Jn what time does tlie ring complete its rcvolutioR on its axis, and, oS course, aroiMMl tbc planet I Whnt is the rate per minute of its motion ? How rapid is this, compared with the motion of tlie Earth's equator 7 Wiiat would be the appearance of the rings, if viewed from the middle zone of the planet, in the alisenoe of the Sun ? How many moons has Satiim 1 How are Saturn, his nngs and satellites, severally, enlightened 7 WtMt arg the daten of their discovery, and the names qf their diveovererg? What are the^ eompurative magnitudes, distances, and times of revolution i What is the position of liieirariHts with respect to the rings of Saturn 7 W?ua doce Laplace imagine retaine the orhte ifaatum*9jlr$i*i»mMait€einthe^fian€ qfhUe^iuUarf^ MO BATBSB» e ter, though the Telocity of the equatorial parts of the former Is mach Ism than that of the latter. This is auttcienUy accounted for by the ftct, that the ringt of Baturn lie in the plane of bis equator, and act more powerfatty upon those parts of his sor&ce than upon any other ; and thos, while they aiii in diminisliinjr the gravity of these parts, also aid the centrifugal force in flattening the poles of the planet. Imieed, had Saturn never revolved upon his axis, the action of the rings would, of itself, have been sufficient to give him the form of an oblate spheroid. ^ The theory of the satellites of Saturn is less perfect than that of the satellites of Jupiter. The difficulty of observing their eclipses, and of measuring their elongations froirl their primary, have prevented astronomers from determining, with their usual precision, their mean distances and revo- lutions. We may remark, with the Christian Philosopher, that there is no planet in the solar system, whose flrmameiit presents such a variety of splendid and magnificent objects as that of Saturn. The various aspects of the seven moons, one rising above the horizon, while another is settin|^, aLd a third approach- insf to the meridian; one entering mto an eclipse, and sfa- other emerging from one ; one appearing as a crescent, and another with a gibbous phase ; and sometimes the whole of them shining in the same hemisphere^ in one bright as- semblage! The majestic motion of the rings, — at one time illuminating the sky with their splendour, and eclipsing the stars ; at another, casting a deep shade over certain regions of the planet, ^d unveiling to view the wonders of the starry firmament, are scenes worthy of the majesty of the Divine Being to unfold, and of rational creatures to coa template. Such displays of Wisdom and Omnipotence, lead us to conclude that the numerous splendid objects connected with this planet, were not created merely to shed their lustre on naked rocks and barren sands ; but that an immense popu- lation of intelligent beings is placed in those regions, to enjoy the bounty, and adore the goodness, of their girat Creator. * The following table exhibits the apparent and mean distances of the sateUlteft from their primary, and the times of their periodical revoluticm. Their dis» tances in miles were computed from their obs'^rved micromettr distances ; the diameter of Saturn's equator being considered equal to 80^('>iiC miles. Why are ostronoiaera leas acquainted with tlie mean distances and revolutioas of Sa- tarn's satellites, tiian with those of Jupiter 1 Describe the firmament of fiatun, as iUa- mJnated by Us lings andsatoUites. BXBSCHKU Ml Satel- Periodic Distance ia Distaaec tn lites. revolution. diameters. milea. 1 Od. 22h. 38tn. 1.540 123,200 2 1 8 63 1.976 158,090 3 1 21 18 2447 195,720 4 2 17 45 3.134 250,720 5 4 12 26 4.377 350.160 6 15 22 41 10.143 811,400 7 79 7 55 29.577 2,366,160 HERSCHEL. Herschel is the most distant planet from the San that has vet been discovered. To the naked eye. it appears like a star of only the 6th or 7th magnitude, ana of a pale, bluish white ; but it can seldom be seen, except in a very fine, clear night, and in the absence of the Moon. ^ As it moves over but one degree of its orbit in 85 days, It will be seven years in passing over one sign or constella- tion. At present,* its mean right ascension is 332^^, and Its decliuation 15f° S. It is therefore in the tail of Capri- corn, making a small triangle with Deneh and Delta Algedi, When first seen by Dr. Herschel, in 1781, it was in the foot of Gemini ; so that it has not yet completed two thirds of a revolution since it was first discovered to be a planet. It is remarkable that this Iiody was observed as far feck as 1690. It was seen three times by Piamstend, once by Bradley, once br Mayer, and eleven times by Lemonnier, who registered it among the stars ; But not one of them suspected it to be a planet. The ineqtialities in the motions of Jupiter and Saturn, which could not be accounted for from the mutual attrac- tions of these planets, lai astronomers to suppose that there existed another planet beyond the orbit of Saturn, by whose action these irregularities were produced. This conjecture was confirmed March 13th, 1781; when Dr. Herschel dis- covered the motions of, this body, and thus proved it to be a planet. Herschel is attended by six moons or satellites, which revolve about him in different periods, and at various dis- * Beginmag of the year 1834. What is the relative distance <^ the planet Herschel from the Sun ? What is its appear' aooe to the naked eye ? In what ctreumstancea can it be seen 7 What is the rate of ita motion in its orint ? What is its present position 7 What was its position when first dis- covered to be a planet 1 How much, then, of its revolution has been completed, since it was first discovered 1 At haw early a dale toae this body observed in the heavenet Who observed it, before it was discovered to be a planet 7 How many times toas It seen by them, respectively t What did they consider it to be 7 What led astronomen to sttKiose that there existed another planet oeyond Saturn 7 When and by whom HsMeod discovered to> be a planet? How many moons has it I 21 0iS BE«80BBU lances. Four of them were discovered by Dr. Herschel, and two by his sister, Miss Caroline Herschel. It is possi- ble that others remain yet to be discovered. Herschel's mean distance from the Sun is 1828 millions of miles ; more than twice the mean distance of Saturn. His sidereal revolution is pe? formed in 84 years and 1 uionth, and his motion in his orbit is 15.600 miles an hour. He is supposed to have a rotation on his axis, in common with the other planets ; but astronomers have not yet been able to obtain any occular proof of such a motion. His diameter is estimated at 34,000 miles; which would make his volume more than 80 times larger than the Earth's. To his inhabitants, the Sun appears only the g-j-g^partas large as he does to us ; and of course they receive from him only that small proportion of light and heat. It may be shown, however, that the ^^tP^^^^ of the Sun's light ex- ceeds the illuminating power of 800 full Moons. This add- ed to the light they must receive from their six satellites, will render iheir days and nights far from cheerless. Such was the celestial system with which our Earth was associated at its creation, distinct from the rest of the starry hosts. Whatever may be the comparative antiquity of our globe, and the myriads of radiant bodies which nightly gem the immense vault above us, it is most reasonable toconclude. that the Sun, Earth, and planets, differ little in the date oi their origin. This fact, at least, seems to be philosophically certain, that all the bodies which compose our solar system muse have been placed at one and the same time in that arrange- ment, and in those positions in which we now behold them ; because all maintain their present stations, and motions, and distances, by their mutuat action on each oilier. Neither could be where it is, nor move as it does, nor appear as we see it^ unless they were all coexistent. The presence of each is essential to the system — the Sun to them, they to the Sun, and all to each other. This fact is a strong indication that their formation was simultaneous. By whom were Herscbel'a satellites discovered 7 What ia tbe distance of Herschel*ii orbit fruni the Sun } How much greater is this distance than that of Saturn 1 In what time is his sidereal revolution performed } What is the rate per hour of his motion in his orbit? lias he a rotation on htsaxis? What is his diameter estimated to be? How much larger would this make his volume than the Earth ? How much less does the Sun fftroear to be to the inlialitants of Herscht 1, than he does to us ? What degree of liglit and heat do they receive from him, compared with that received by the Earth ) To the light (tT aow many full mouns is this debtee of light equal ? What reason have we to suppoM tbat tbe difSjient bodies of the suliur system wrere created at tJlie same time} CMffiT«. Md COMETS Comets, whether viewed as ephemeral meteors, or as substantial bodies, forming a part of the Solar system, are objects of DO ordinary interest. When, with un instructed gaze, we look upwards, to the clear sky of evening, and behold, among the multitudes of heavenly bodies, one, blazing with its long train of light, and rushing onward towards the centre of our system, we insensibly shrink back as if in the presence of a supernatu* ral beings But when, with the eye of astronomy, we follow it through its perihelion, and trace it far off, beyond the utmost verge of the solar system, till it is lost in the infinity of space, not to return for centuries, we are deeply impressed with a sence of that power which could create and set in motion sach bodies. Comets are distinguished from the other heavenly bodies, bv their appearance and motion. The appearance of the planets is globular, and their motion around the Sun is near- ly in the same plane, and from west to east ; but the comets have a variety of forms, and their orbits are not confined to any particular part of the heavens ; nor do they observe any one general direction*. The orbits of the planets approach nearly to circles, while those of the comets are very elongated ellipses. A wire hoop, for example, will represent the orbit of a planet. If two opposite sides of the same hoop, be extended, so that is shall be long and narrow, it will then represent the orbit of a comet. The Sun is always in one of the foci of the comet's orbit. There is, however, a practical difficulty of a peculiar nature which cn> barrasses tlie eotuiionofthe question as to the form nf the coinetary orbits. It so happens that the only part of the course of a comet which can ever be visible, is a portion throughout which the ellipse, the parabola, and hy- f erbolo, so closely resemble each other, that no observalious can be obtain- ed witli sufficient accurucy to enable us to distin<$uish them. In fact, the ob* served path of any comet, while visible, may belong either to an ellipse, iKl- jpabola, or hyperbola. That part which is usually brighter, or more opaque^ than the other portions of the comet, is called the nucleus. This is surrounded bv an envelope, which has a cloudy, or hairy appearance, l^hese two parts constitute the body, and, in many instances, the whole of the comet. What fbclincB does the contemplation of comets naturally excite? How are comets dist mniislied frum the other heavenly bodies 1 Describe their appearance und motiuo. Of what three parts may comets be eoosideced to be eomposed ) Describe these paita ■evemiiy. 244 dbuisTB. Most of them, however, are attended hy a long tram, called the tail ; though some are without this appendage, and as seen by the naKed eye, are not easily distinguished from the planets. Others, again, have no apparent nucleus, and seem to be only globular masses of vapour. Nothing is known with certainty of the composition of these bodies. The envelope appears to be nothing more than vapour, becoming more lummous and transparent when approaching the Sun. As the comets pass between us and the fixed stars, their envelopes and tails are so thin, that «tars of very small magnitudes may be seen through them. Some comets, havin^o nucleus, are transparent throughout their whole extent. The nucleus of a comet sometimes appears opaque, and it then resembles a planet. Astronomers, however, are not agreed upon this point. Some affirm that the nucleus is always transparent, and that comets are in fact nothing but a mass of vapour, or less condensed at the centre. By others it is maintained that the nucleus is sometimes solid and opaque. It seems probable, however, that there are three classes ox comets; viz. : 1st. Those which have no nucleus, being transparent throughout their whole ex- tent ; 2d. Those whicn nave a transparent nucleus; and, 3d. Those having a nucleus which is solid and opaque. A comet, when at a distance from the Sun^ viewed through a good telescope, has the appearance oi a dense vapour surrounding the nucleus, and sometimes flowing far into the regions of space. As it approaches the Sun, its light becomes more bniiiaiit, till it reaches its perihelion, when its light is more dazzling than that of any other celes- tial bodv, the Sun excepted. In this part ot its orbit are seen to the best advantage the phenomena of this wonderful* body, which has, from remote antiquity, been the spectre of alarm and terrour. The luminous train of a comet usually follows it, as it approaches the Suti, and goes before it, when the comet recedes from the Sun ; sometimes the tail is considerably curved 'towards the region to which the comet is tending, and in some instances, it has been observed to form a right angle with a line drawn from the Sun through the centre of the comet. The tail of the comet of 1744, formed near- ly a quarter of a circle ; that of 1689 was curved like a Hare all comets these three parts? What apparent differences may be perceived in the composition of diiierent comets ? Into what classes, with reiercnee to their compoti* tipD, may comets be divided 7 Describe the diflerent appearances of comets at difrcreDt lUitances from the Sun. In what poxLof their orbit are their phenomena seen to the belt MwnUue? Whnt is usually the direction -t^f the Juinj" tfOQ of tfi« taU of the comet of 1744 7 Of that of 1S8» i COMETS. 245 Turkish sabre. Sometimes the same comet has several taJi=. That of 1744 had, at one time, no less ihan siXj which appeared and disappeared in a few days. The comet of 1823 had, for several days, two tails ; one ex- tending towards the Sun, and the other in the opposite direction. Comets, in passing among and near the planets, are materially drtfNvn aside from their courses, and in some cases have their orbits entirely changed. This is remarka- bly true in regard to Jupiter, which seems by some strange fatality to be constantly in their way, and to serve as a per- petual stumbling block to them. " The remarkable comet of 1770, which was found by Lexell to revolve in a moderate ellipse, in a period of about five years, actually ^or entarigied aiuong the satellites of Jupiter, and thrown out of iis orbit by the attrac* •lions of tliat planet," and has not been heard of since. — Herschel^ p. 310. By this extraordinary rencontre, the motions of Jupiter's satellites sufTer* ed not the least perceptible derangement ,*— a suiScieat proof of Uie aeriform nature of the comet's mass. It is clear from observation that comets contain very little matter. For they produce little or no effect on the motion of the planets when passing near those bodies ; it is said ibat a comet, in 1454, eclipsed the moon ; so that it must have been very near the Earth ; yet no sensible effect was observed to be produced by this cause, upon the mo- tifiii of the Earth or the' Moon. The observations of philosophers upon comets, have as yet detected nothing of their nature. Tycho Brahe and Appian supposed their tails to be produced by the rays of the Sun, tiansniitted through the nucleus, which they sup- posed to be transparent, and to operate as a lens. Kepler thought they were occasioned by the atrposphere of the comet, driven off by the impulse of the Sun's rays. This opinion, with some modification, was also maintained by Euler. Sir Isaac Newton conjectured, that they were a thin vapour, rising from the heated nucleus, as smoke as- cends from the Earth ; while Dr. Hamilton supposed them to be streams of electricity. "That the luminous part of a comet," says Sir John Herschel, "is some- thing in tiie nature of a smoke, fog, or cloud, suspended in a transpareut aiujosphcre, is evident from a fact which has been oAen noticed, viz. that How many tails liad the comet of 1744 at one time, and how long did they continue to appear? How many had that of IS23, and what was their direction 7 When comets pmm near planets, how does the attraction of tbo planets aftect them 7 In regard to what pla- net is this remarkably tme? Mention an example of comets being so affected. What fact ennnfcted xoith thi9ca$e proven the aeriform nature of the coM^t*a mass 7 How IS it clear from oliservation that comets contain very little matter 7 What were the opi- nions of rycho Brahe, Appian, Kepler, Euler, Sir Isaac Newton, and Dr. Hamilton, in rpcrard to the tails of comets 7 \V?iat wag She opinion ttf Sir John Ilertckel, and on tphat founded 7 21* d46 COMfiTlU ths psrtion of the tall where it comes up to, Md eunroande the he*'!; is jd separated from it by an interval less liiminons ; as we often see one layer of clouds laid over another with a considerable clear space between them." And again—" It follows, that these can only be regarded as threat masses of ihin vapour, susceutible of being penetrated through their whole substanco by the sunbeams." Comets have always been considered by the ignorant and superstitious, as the harbingers of war, pestilence, and fam- ine. Nor has this 6piQion been, even to this day, confined to the unlearned. It was once universal. And when we examine the dimensions and appearances of some of these bodies, we cease to wonder that they produce^ universal alarm. According to the testimony of the early writers, a comet which could be seen in day light with the naked eye, made its appearance 43 years before the birth of our Saviour. This date was just after the death of Ceesar, and by the Ro- mans, the comet was believed to be his metamorphosed soul, armed with fire and vengeance. This comet is again mentioned as appearing in 1106, and then resembling the Sun in brightness, being of a great size, and having an im- mense tail. In the year 1402, a comet was seen, so brilliant as to be discerned at noon-day. In 1456 a large comet made its appearance. It spread a wider terrour than was ever known before. The be- lief was very general, among all classes, that the comet would destroy the Earth, and that the Day of Judgment was at hand ! This comet appeared again in the years 1531, 1607, 1682, 1758, and is now approaching the Sun witli accelerated velocity. It will jmuss its perihelion in November, 1835, and every 75^ years thereafter. We now [October, 1835,] see this self same comet, so often expelled the Church of Rome, returning to re* assert his claim to a fellowship with the solar family. At the time of the appearance of this comet, the Turks extended their victorious arms across the Hellespont, and seemed destined to overrun all Europe. This added not a little to the general gloom. Under all these impressions, the people seemed totally regardless of the present, and anxious only for the future. The Romish Church held at this time unbounded sway over the lives, and fortunes, and consciences of men. To prepare the world for its expected doom, Pope Calixtus III. ordered the Ave Maria to be re-» peated three times a day. Instead of two. He ordered the church bells to be rung at noon, which was the origin of , How have eometa been regarded by the ignorant and supcTStitious 7 Mention some of toe most remarkable comets which have appeared. Describe tfaem severaUy. and lelato m what roap-ter they were severally regarded f What U the periodic tim* ofthH comet f that practice, ao umvertal in ChristiaD ehniehes. To the Ave Maria, ihe prayer was added — " Lord, save us from tne Devil, the Turk, and ihe Comet :" and ODce, each day^ ihese three obnoxious persooages sufiered a regular excoii> The pope and clergv, exhibiting such fear, it is not a matter of wonder that it became the ruling passion of the multitude. The churches and coovents were crowded for cotifession of sins ; and treasures uncoualed were poured inio the Apostolic chamber. The comet, after suffering some months of daily cursing and eicomraunicalion, began to show signs of retreat, ana Boon disappeared ffom those eyes in which it found no fa- vour. Joy and tranquillity soon returned to the faithful sub- jects of the pope, but not so their money and lands. The people, however, became satisfied that iheir lives, and the safety' of the world, hud been cheaply purchased. The pope, who had achieved so signal a Victory oven the mon- ster of the sky, had checked the progress of the Turk, and kept, fur thepresenl, his Salanic majesty at a safe distance ; while the Church of Rome, retaining her unbounded wealth, Was enabled to continue thai influence over her follower*. which she reiajns, in part, to this dav. ^^ The comet of 16S0 would have been still more alarm- iojt than that of 1456, had not science robbed it of its ter- rours, and history pointed to the signal failure of its prede- cessor. This i^omet was of the Targesi sixe, and bad a tail who>ie enormous length was moie than ninety-tix mil- lions of mileg. At its greatest distance, il is 13,000 millions of miles from the Sun; andat its nearest approach, only 574,000niUe* from his centre ;* or about 130,000 miles from his surface. Iq that part of its orbit which is nearest the Sun, it flies to£^i« *v«lDqtj'oripMa,U8nidn :4f hour. 248 COMETS. nrith the amazing swiftness of 1,000,000 miles in an hour, and the Sun, as seen from it, appears 27,000 times larger than it appears to us ; consequently, it is then exposed to a heat 27,000 times greater than the solar heat at the Earth. This intensity of heat exceeds, several thousand times, that of red-hot iron, and indeed all the degrees of heat that we are able to produce. A simple mass of vapour, exposed to a thousandth part of such a heat, would be at once dissipated in space — a pretty strong indication that, however volatile are the elements of which comets are composed, they are, nevertheless, capable of enduring an inconceivable intensity of both heat and cold. This is the comet which, according to the reveries ot Dr. Whiston and others, deluged the world in the time of Noah. Whiston was the friend and successor of Newton : but, anxious to know more than is revealed, he passed the bounds of sober philQsophy, and presumed not only to fix the residence of the damned, but also the nature of their punishment. According to his theory, a comet was the awful prison-house in which, as it wheeled from the remotest regions of darkness and cold into the very vicinity of the Sun, hurrying its wretched tenants to the extremes of per- ishing cold and devouring fire, the Almighty was to dispense the severities of his justice. Such theories may be ingenious, but they have no basis of facts to rest upon. They more properly belong to the chimeras of Astrology, than to the science of Astronomy. When we are told by philosophers of great caution and high reputation, that the fiery train of the comet, just allud- ed to, extended from the horizon to the zenith ; and that that of 1744 had, at one time, six tails, each 6,000,000 of miles long, and that another, which appeared soon after, had one 40,000,000 of miles long, and when we consider also the inconceivable velocity with which they speed their liight through the solar system, we may cease to wonder if, in the darker ages, they have been regarded as evil omens. But these idle phantasies are not peculiar to any age or country. Even in our own limes, the beautiful comet of 1811, the most splendid one of modern times, was generally considered among the superstitious, as the dread harbinger What i9 the degree of heat towbich the oomet (^1$80 is exposed, %vhen In iU perihelion, compared to tliat experienced at the Earth ) What is the intensity of auch a degree of heat, oompan-d with that of red-hot iron, or with any degree of heiit which we are 8ble to produM? ,^V''^* "l.^'ence may be derived from this feet in retiHrd to the composition of •mj^ ^ ot What event ivaa the comet of 1811 oumidered. io our countiy. to be the bar ^^^b. ^ COHBTS. iM of the war which was declared in the following spring. It is well known that^ an indefinite apprehension of a more dreadful catastrophe lately pervaded both continents, m an- ticipation of Biela's comet of 1832. The nucleus of the comet of 1811, according to observa- lions made near Boston, was 2^617 miles in diameter^ cor- responding nearly to the size of the Moon. The brilliancy with which it shone, was equal to one tenth of that of the Moon. The envelope, or aeriform covering, surrounding the nucleus, was 24,000 miles thick, about five hundred times as thick as the atmosphere which encircles the Earth; making the diameter of the comet, including its envelope, 50,617 miles. It had a very luminous tail, whose greatest length was one hundred million of miles. This comet moved, in its perilielioa, with an almost inconceivable velocity— fifteen liandred times.grcater than that of a ball banrting from the mouth of a cannon. According to Regiomoiitanus, the comet of 1472 moved over an ai ^ of 120^ in ono dav. Brydonc observed a comet at Palermo in 1770^ which pasg- ed through CO^ or a great circle in the heavens In 24 hours. Another comet, which appeared in 1759, passed over 41° in the same time. The conjecture or Dr. Haliey therefore seems highly probable, tiiat if a body of such a aisai having any considerable density, and moving with such a velocity, were to -, strike our Earth, it would instantly reduce it to chaos, mingling its elements in ruin. Tlie transient effect of • eomet passing near the Earth, could scarcely amount to any great convulsion, says Dr. Brewster : but if the Eaith were actuatlv to receive a shoclc from one of these bodies, the consequences would be awful. A new direction would be given to its rotary motion, and it would revolve around a new axis. The seas, forsaking their beds, would be hurried, by their centrifugal force, to the new equatorial regions : islands and continents, the abodes of men and auimals, would be covered by the naiversal rush of the waters to the new equator, and every vestige of ho* man industry and genius would be at Once destroyed. y The chances against such an event, however, are so very /* numerous, that there is no reason to dread its occurrence. The French government, not long since, called the atten- tion of some of her ablest mathematicians and astronomers to the solution of this problem ; that is, to determine, upon mathematical pnnciples, how m.any chances of collision the Earth was exposed to. After a mature examination, they re- ported,—" We have found that, of 281,000,000 of chances, there is only one unfavourable, — there exists but one which can produce a collision between the two bodies." "Admitting, then," say they, "for a moment, that the comets which niay strike the Earth with their nucleuses, would annihilate the whole human race; the danger of death to each individual, resulting from the ap- Deicribe this comet Qlve tomt examjiie* ef the velocity of comett. What would probably he the dfect upon the Kartht should a comet ttrike it 7 What does Dr. Brew- uereay would be the effect efa comet paeaing near the Earth 1 But if the Earth were actzuUlyto receive a ehockfrom a cotnet, what doee he *ay would be the reaul'at How did the French mathomaticiana and astronomera find tlie chances of a colluion b^ tween the Earth and comets to stand 7 What, then, on the eupposUion that a etrokev a comet would annihilate the whole human race, i$ the danger of death to each M" dividual, reeuUtng from the appearance qfan wiknown eomet ? ^KtO COMETS. •petrance of an unknown eom«l, woaki he exactly equal lo the rkk tie wt^uid run, if in an urn there was only one single white oall among a total num- biT of 281,000,000 balls, and that his cnndeuinalion to death wmild be the inevitable consequence of the white ball being prorluced at the first draw> ing." We have before stated that comets, unlike the planets, observe no one direction in their orbits, but appruaca to, ana recede from their great centre of attraction, in every possi- ble direction. Nothing can be more sublime, or better calculated to fill the mind with profound astonishment, than to contemplate the revolution of comets, while in tkat part of their orbits which comes within the sphere of the tele- scope. Some seem to come up from the immeasurable depths below the ecliptic, and, having doubled the heavens' mighty cape, again plunge downward with their fiery trains, " On the long travel of a thousand years." Others appear to come down from the zenith of the uni- verse to double their perihelion about the Sun, and then re- ascend far above all human vision. Others are dashing through the solar system in all possi- ble directions, and apparently without any undisturbed or undisiurbing path prescribed by him who guides and sus- tains them all. Until within a few years, it was universally believed that the periods of their revolutions must necessarily he of prodi- |[ious length; but within a few years, two comets have Been discovered, whose revolutions are performed, compa- ratively, within our own neighbourhood. To distinguish them from the more remote, they are denominated the comets of a short period. The first was discovered in the constella- tion Aquarius, by two French astronomers, in the year 1786. The same comet was again observed by Miss Caro- line Herschel, in the constellation Cygnus, m 1795, and a^ain in 1805. In 1818, Professor Encke determined the dimensions of its orbit, and the period of its sidereal revolu- tion; for which reason it has been called ^^ Buckets Cornet.^* This comet performs its revolution around the Sun in about J years and 4 months,* in an elliptical orbit which lies wholly within the orbit of Jupiter. Its mean distance from the Sun is 212 millions of miles; the eccentricity of its orbit is 179 * Owing to the disturtring influences of tlie surrounding planets, the periodic return of Jiu comet, liice that of all others, is liable to be iuLStenea or retarded several days. Iti ,tenoa vanes from about 12U3 to 12IS days. What Is the direcUon of comets in their orbits ? What has been, until within a few years, tbe universal opinion in resard ti> the length of the times of tlieir revolution 7 Wh* i?*.?®V* . ■«•"? "P«3«« prevail now ? What an? these two comets denominated? Re- lwS^«r&'™te?^fpj:tf^'*^*'"'- Why is it called Enclce's comet? Whatk SSSST 2JlirJSI« fi,^- IJ??»''''f ? "^"^ ' J^^^ '^ the form of its orbit, and what it» &SSSr^Sn't^^S^^'^FS!'^^''''' " ^^^-^--t-smean istanoe froo, COlifiTS. 251 mtiUons of miles ; consequently it is 368 millions of miles nearer the Sun in its perihelion, than it is in its aphelion. It was visible throughout the United States in 1825, when It presented a fine appearance. It was also observed at its next return in 1828; but its last return to its perihelion, on the eth of May, 1832, was invisible in the United States, on account of its great southern declination. - «^"** The second "Comet of a short period," was observed in 1772; and was seen again in 1805. It was not until its re-appearance in 1826, that astronomers were able to determine the elements of its orbit, and the exact period of its revolution. This was successfully accomplished by M. Biela of Josephstadi ; hence it is called Bield's Comet According to observations made upon it in 1805, by the cele- brated Dr. Olbers, its diameter, including its envelope, is 42,280 miles. It is a curious fact, that the path of Bie- la's comet passes verv near to that of the Earth ; so near, that at the moment the centre of the comet is at the point nearest to the^Earth's path, the matter of the comet extends beyond that path, and includes a portion within it. Thus, if the Earth were at that point of its orbit which is nearest to the path of the comet, at the same moment that the comet should be at that point of its orbit which is nearest to the . path of the Earth, the Earth would be enveloped in the ne- bulous atmosphere of the comet. With respect to the effect which might be produced upon our atmosphere by such a circumstance, it is impossible to offer any thing but the most vague conjecture. Sir John Herschei was able to distinguish stars as minute as the 16th or 17th magnitude through the body of the comet! Hence it seems reasonable to infer, that the nebulous matter of which it is composed, must be infinitely more attenuated than our atmosphere ; so that for every particle of cometarv matter which we should inhale, we should inspire millions of par- ticles of atmospheric air. This is the comet which was to come into collision with the Earth, and to blot it out from the Solar System. In re- turning to its perihelion, November 26th, 1832, it was com- puted that it would cross the Earth's orbit at a distance of ■ ■ ■ - . — ■ -, ^^ ^ ^ How much nearer the Sun, then, is tlie comet, when in its perihelion than when in ita tphelion ? In wluit years lias this oxnet been seen id the United State»l Why was it not visible in the United States at the time of its retimi in 183-2 7 Relate the history of the discovery of the second comet of a short period 1 Why is it called Bicia's comet } Whatt according to the observations of Dr. Olbers in 1805, was the diameter of Biela's comet, in- cliuting the envelope 7 How near does the path of Bieia's comet lie to tliat of the Earfhl >Vbat would be tlie cfl^t upon our atmosphere should tlie nebulous atmosphert? of the Minet envelope it 7 What reason have we to suppose that it is more attenuated thtui our ttmosphere? It was predicted that this comet would come into collision with the Earth ; what were the jcrounds of probability that such an event w *^d take place, an4 why did it not I 289. coMrr^ only 18,500 miles. It is eyident that if the Earth had been in that part of her orbit at the same time with the comet, oar atmosphere would have mingled with the atmosphere of the comet, and the two bodies, perhaps, have come in contact. But the comet passed the Earth's orbit on the 29th of Oc- tober, in the 8th degree of Sagittarius, and the Garth did not arrive at that point until the 30th of November, which was 32 days afterwards. If we muhiplv the number of hours in 32 days, by 68,000 (the velocity or the Earth per hour,) we shall find that the Earth was more than 52,000,000 miles behind the comet wJien it crossed her orbit. Its nearest approach to the Earth, at any time, was about 51 millions of miles ; its near- est approach to the Sun, was about 83 millions of miles. Its mean distance from the Sun, or half the longest axis of its orbit, is 337 millions of miles. Its eccentricity is 253 mil- lions of miles ; consequeody, it is 507 millions of miles nearer the Sun in its perihelion than it is in its aphelion. The period of its sidereal revolution is 2,460 days, or about 6f years. Althoagh tbe cometd of Encke and Biela are ohjects of very ^eat inter* est, yet their short periods, the limited space within which their morion is circumscribed, and consequently the very slight disturbance which they sustain from the attraction of the planets, render them uf less interest to physical astronomy than those of longer periods. They do not, lilce them, rush from the invisible and inaccessible depths of space, and, after sweeping our system, depart to distances with tlie con- ception of which the imsigination itself is confounded. They possess none of that grandeur which is connected with whatever appears to brealc through the fixed ofder of the universe. It is reserved lor the comet of Ilalley alone to afford the proudest triumph to those powers of calculatioo bjr whicli we are enabled to follow it in the depths of space, two thousand millions of miles beyond the extreme verge of the solar system ; and, nof- tvithstanding disturbances which render each succeeiiing period of its return different from the last, to forelel that return with precision. The following representation of the entire orbit of Biela's comet, was obtained from the Astronomer Royal of the Greenwich Observatory. It shows not only the space and position it occupies in the solar system, but the points where Its orbit intersects all the planetary orbits through which it passes. By this, it is seen that its perihelion lies between the orbits of the Earth and Venus, while its aphelion extends a little beyond that of Jupiter. What was its nearest approadi to the Eaith at any time t What its nearest approa^ totboSuni .Whatibiineandiatwice fiom the Sun? What its eccentricity I Whtl; COMETS. Fig. 20. 22 954 ooHETa This diagram not only exhibits the coarse of the comet at its last retara, but also denotes its future positions on the first day of every year during its next revolution. It is also apparent that it will return to its perihelion again in the autumn of 1839, but not so immediately in our vicinity as to be the proper cause of alarm. To be able to predict the very day and circumstances of the return of such a bodi- less ana eccenttic wanderer, after the lapse of so many years, evinces a perfection of the astronomical calculus that may justly challenge our admiration. "The re-appearance of this comet," says Hersche), ^ whose return in 1832 was made the subject of elaborate calculations by mathematicians of the first eminence, did not disappoint the expectation of astronomers. It is hardly possible to imagine any thing more striking than the ap- pearance, after the lapse of nearly seven years, of such an all but imperceptible cloud or wisp of vapour, true^ however, to itsjpreaicted time and place, and obeying laws like those .^hich regulate the planets," HerscheL whose Observatory is at Slottffh, England, observed the daily progress of this comet from the 24th of September, uutil its UiKappearance, eompared its ttdual position from day to day with its calculated positioo, and foand them to acree within four or five minutes of time in li^ht ascen* sion, and within a Jew seconds of declination. Its position, tlien, as ropre> sented on a planisphere which the author prepared fur his pupils, and af- terwards pablisheo^ was true to within a less space than one third of its projected diameter. Like some others that have been observed, this comet Aas DO luminous inXn by which it can be easily recognized by the naked eye, except when it is very near the Sun. This is the reason why it was not more generally observed at its late return. AUhoiwh this comet is usually denominated " Diela's comet," yet it seems that AL Garobart, director of tlie Observatory at Marseilles, is equally en- titled to the honour of identifying it with the comet of 1772, and of ISIC He discovered it only 10 days after Biela, and immediately set abonc calcu- lating its elements from his own observations, wiiich are thought to equal, if they do not surpass, in point of accuracy, those of every other a:** tronomer. Up to the beginning of the 17th century, no correct no- tions had been entertained in respect to the.paths of comets. Kepler's first conjecture was that they moved in straight lines; but as that did not agree with observation, he next concluded that they 'vyere parabolic curves, having the Sun near the vertex, and running indefinitely into the regions ot space at both extremities. There was nothing in the ob« servations of the earlier astronomers to fix their identitv, or to lead him to suspect that any one of them had ever oeen seen before ; much less that they formed a part of the solar ■ — ^ — ' • ■ _ _ - . I L I I Ifrlien win this oometietuiB again 7 How much did its acttuU potUion from dav io taift as observed by Hersehslt differ from its cdleulatcd position J Wfw was it not Mora gmuraOy observed at its tats return 7 What astronomer besides Biela id^ti- Modn wWi the eomet qf itts aiul isob 9 What were the oiNnioas of astronomers in re- fS^i!® ^ ^^ ofponeU. up to tbf bagiiiQiiicor tJit irUioooturr 7 What wfis Ksite's nnuiMns on ibis siibjsot ) COMETS* SS5 system, revolving about tae Sun in elliptical orbits that re- turned into themselves. This grand discovery was reserved for one of the most industrious and sagacious astronomers that ever lived — this was Dr. Halley, the contemporary and friend of Newton. When the comet of 1682 made its appearance, he set him- self about observinff it with great care, and found there was a wonderful resemblance between it and three other comets that he found recorded, the comets of 1456, of 1531, and 1607. The times of their appearance had been nearly at equal and regular intervals ; their perihelion distances were nearly the same ; and he finally proved them to be one and the same comet, performing its circuit around the Sun in a period varying a little from 76 years. This is therefore called Halley^s comet. It is the very same comet that filled the eastern world with so much consternation in 1456, and became an object of such abhorrence to the church of Rome. Of all the comets which have been observed since the Christian era, only three have had their elements so well determined that astronomers are able to fix the period of their revolution, and to predict the time and circumstances of their appearance. These three are, Encke's, whose last revolution about the Sun was performed in 1212 days; Biela's, whose period was 2461 days ; and Halley 's, whicn is now accomplishing its broad circuit in about 28,000 days. Encke's and Halley's will return to their perihelion tne present year (1835), and Biela's in 1839. ^ Halley's comet, true to its predicted time uid place, is now (Oct 183&) visible in tite evening iilcy. But we behold none of those phenomena which threw our ancestors of the miiJdle ages into agonies of superstitious terrour. We see not the eometa hor ferula magmttidini*^ as it appeared in 1306, nor that tail of enormous length/ which, in 1456, extended over two thirds of tlie interval between the horizon and the zenith, nor even a star as briffiant as was the same comet in 1682; with its tail of 30^. >^ts mean distance from the Sun is 1,713^700,000 roilesj the eccentricity of )iM orbit is 1,669^000,000 miles ; consequendy it is 3,31&000,000 miles far- ther from tlie Sun in its aphelion than it is in its perihelion. In the latter case, its distance from him is only 66,700^000 miles ; but in the former, it la 3,371,70Ufl00 miles Tlierefore, though its aphelion distance be great, its mean distance is less than that of Ilerschel ; and great as is the aphelion distance, it is but a very small fraction less than one five-thaueandth part of that distaQce from the Bun, beyond which the verv nearest of the fixed stars must be situated ; and, as the determination of their distance is nega> Who first discovered the idcntitjr of comets 7 Relate the manner by which he came to this djflcovcry. How manjr of all the comets observed since the Chnstian era, have had their ekinents so well deteraiined, that astronoroers are able to fix the period of their le- volutions, and to predict the time and circumstances of their appearance I What omnels are these? In what time do they accomplish their revohitions? When will tbevt save- rally, return to tlieir pehbclion ? What comet U nmo {Oct. 183S) vieibU? What ars the nwarit and the aphelion and perihelion dittancee fffHaUey*a comet from the 8uh 7 What part uf the dietance beyond which ths neareet of the fixed etare mmt be pA^ ud, U Ut aphelUm dietance 7 860 LAW OF UNIVERSAL GRAVITATION tire and not positive, tbe nearest of them may be at twice or ten times that distance. The nomber of comets which have been observed since the Christian era, amoants to 700. Bcarcelj a year has passed without the observation of one or two. And since multitudes of them must escape observation, by reason of their traversing that part of the heavens whicli is above the hori- zon in the day time, their whole number is probably many thousands. Comets so circumstanced, can only become visible by the rare coincidence of a total eclipse of the Sun — a coincidence which happened, as related by Seneca, 60 years before Christ, when a laiige comet was actually observed Tory near the Son. f But M. Arago reasons in the following manner, with respect to the num- ber of comets : — ^The number of ascertaioed comets, which, at their least distances, pass within the orbit of Mercury, is thirty. Assuming that the comets are uniformly distributed throughout the soiar system, there wiU be 117,649 times as many comets included within the oibtt of Herschel, as there are within the orbit of Mercury. But as there are 30 within; the orbit of Mercury, there must be 3,629,470 within the orbit of Herschel !/ • Of 97 comets whose elements have been calculated by astronomers, 24 Sassed between the Sun and the orbit of Mercury ; 33 between the orbits of [ercnry and Venus ; 21 between the orbits of Venus and the Earth ; 15 between the orbits of Ceres and Jupiter. Forty-nine of these comets move from east to west, and 48 in the opposite direction. The total number of distinct comets, whose paths during the visible part of Uieir course had been ascertained, up to the year 183^ was one hundred and thirty-seven. What regions these bodies visit, when they pass beyond the limits of our view; upon what errands they come, when they again revisit the central parts of our system ; what is tne difference between their physical constitution and that of the Sun and planets ; and what important ends they are destined to accomplish, in the economy of the universe, are inquiries which naturally arise in the mind, but which sur- pass the limited powers of the human understanding at pre* sent to determine. CHAPTER XX. OP THE FORCES BY WHICH THE PLANETS ARE RETAINED IN THEIR ORBITS. Having described the real and apparent motions rf the bodies which compose the solar system, it may be interest- ing next to show, that these motions, however varied or com- I)lex they may seem, all result from one simple principle, oi aw, namely, the » What ia iht number qf comets which have been observed since the Cfuristion era? Why must some of than escape observation ? Hoto great is probably their actual nvmber 7 In what case aUme can comets which traverse the horizon in the day time became visible! Mention an instance qf a comet thus becoming visiKel Wfutt is the reasoning qfM. Arago in regard to the number of comets ? Describe the trade among the orbits of the planets, qfthe 97 comers whose elements have been calculated by astronomers. In what direction do they move 7 What, up to the year l»«, was the whole number qf distinct comets, whose patht during the visible part ofthHrcourse,haa been determined 7 By what pdndple, or law, are tbe idanets re- valued in tbeu onata I LAW OP CNIVCRSAL GRAVITATION. 257 LAW OF DNITERSAL GJlAVITATION. It IS said, that Sir Isaac Newton, when he was drawing to a close the demonstration of the ^reat truth, that gravity is the cause which keeps the heavenly bodies in their orbits, was so much agitated with the magnitude and importance or the discovery he was about to make, that he was unahle to proceed, and desired a friend to finish what the intensity of his feelings did not allow him to do. By gravitationis meant that universal law of attraction, by which every particle oi matter in the system has a tendency to every other particle. This attraction, or tendency of bodies towards each other, is in proportion to the quantity of matter they contain. The Earth, being immensely large in comparison with all other substances in its vicinity, destroys the effect of this attrac- tion between smaller bodies, by bringing them all to itself. The attraction of gravitation is reciprocal. All bodies not only attract other bodies, but ^re themselves attracted, and both according to their respective quantities of matter. The Sun, the largest body in Our system, attracts the Earth and all the other planets, while they in turn attract the Sun. The Earth, also, attracts the Moon, and she in turn at- tracts the Earth. . A ball, thrown upwards from the Earth, is brought again to its surface ; the Earth's attraction not only counterbalancing that of the ball, but also producing a motion of the ball towards itself. This disposition, or tendency towards the Earth, is mani- fested in whatever falls, whether it be a pebble from the hand, an apple from a tree, or an avalanche from a moun- tain. All terrestrial bodies, not excepting the waters of the ocean, gravitate towards the centre of the Earth, and it is by the same power that animals on all parts of the globe stand with their feet pointing to its centre. The power of terrestrial gravitation is greatest at the earth's surface, whence it decreases both upwards and downwards ; but not both ways in the same proportion. It decreases upwards as the square of the distance from the Earth's centre ncreases ; so that at a distance from the centre equal to twice the semindiameter of the Earth, the gravitating force would be only one fourth of what it is at the surface. But below the surface, it decreases in the direct rcUio of the dis Who djacovered tbui great truth, and how was he afibeted in view of it? What fo meant by gravitatioQ? To what ia it prmmtioned? Give Mme example. How n it known that the attractioa of gravitation ia redproeal 1 Give aome examples to lUustr^ tUs principle. Where is the power of terrastrial gravitation the greatest? From tmi Kint, does the power decnase eqtuiUyt both upwards and downwanul What » the IT of decrease upwards 7 Give an example. 'W^wt is the law of decrease aotomtforw? Give an ewmplei 25* 268 LAV OF UNtYERSAL ORAVITATIOXr* tance from the centre ; so that at a distance of halt a semi diameter from the centre, the gravitating force is but half what it is at the surface. Weight and Gravity, in this case, are synonymous terms. We say a piece of lead weighs a pound^ or 16 ounces ; but if by any means it could be raised 4000 miles above the surface of the Earth, which is about the distance of the surface from the centre, and consequently equal to two semi-diameters of the Earth above its centre, it would weigh only one fourth of a pound, or four ounces ; and if the same weight could be raised to an elevation of 12.000 miles above the surface, or four semi-diameters above tne centre of the Earth, it would there weigh only one sixteenth of a pound, or one ounce. The same boay, at the centre of the Earth, being equally attracted in every direction, would be without weight ; at 1000 miles from the centre it would weigh one fourth of a pound ; at 2000 miles, one half of a pound ; at 3000 miles, three fourths of a pound ; and at 4000 miles, or at the sur- face, one pound. It is a universal law of attraction, that its powtr decretuea as the square of the distance increases. The converse of this is also true, viz. The potoer increases, as tfie square of the distance decreases. Giving to this law the forin of a practical rule, it will stand thus : 7%e gravity of bodies above the surface 6f the Sarth, decreases in a dupU ea/e ratio^ Cor as the squares of their distances} in semi-diameters of the earthy from the earth's centre. That is, when the gravity is increasing^ multiply the weight by the square of the distance ; but when the gravity is decreasing^ divide the weight by the square of the distance. Suppose a body weighs 40 pounds at 2000 miles above the Earth's sur- fiu^e, what would it weigh at the surface, estimating the Earth's seui-diameter at 4000 miles 1 From the centre to the given height, is 1^ semi-diameters : the square of 1^, or 1.5 is 2.25, which, multiplied into the weight, (40^) gives 90 pounds, the answer. Suppose a body which weighs 256 pounds upon the surface of the Barth, be raised to the distance ot the Moon, (240,000 miles,) what would be its weight. Thus, 4000^0,000(60 serai diameters, the square of which is 3600. As the gravity, in this case, is decreasing, divide the weight by the square of the distance, and it will give 3600)256(1 -16th of a pound, or 1 ouilbe. 2. To find to what height a given weight must be raised to lose a certuo portion of its weight KuiM.^Divide the weight at the surface^ by the required weight, and ex- tract the square root of the quotient. Ex.. A bov weighs 100 pounds, bow high must he be carried to weigh but 4 pounds? Thus, 100 divided by 4, gives 26, the square root of which is 5 semi-diameters, or 20,000 miles above the centre. Bodies of equal magnitude do not always contain equal WttaX is the relation between weight and gravity? Illustrate it by some exaxRpfes. WTuUt then, i« the general lau> in regard to the increase and decrease f^oitraetion? Bow may this law be expreseed^in the form qf a praeticcU rule 7 Suppose, for ex- ample, .he semi-diameter qf the Earth be estinuUed, in round nwnbers, at 4000 miies, and thaa body, elevated 2000 mUes above if surface, should weigh 40 pounds, what would the same body weigh, if brought to the EartWe surjdcel Suppose a body which weighs sss pounds upon the surfacn qf the Earth, be raised to the distance qf the Mnon, what wotUd be ita weight at such an elevation 7 [The pupil should be Te- qiiired to give tlie calculation, as well as the answer.] By what rule can, we determine we height to which a body must be raised, in order to ite losing a certain portion of Hf^iSl^^i Give an example. Do bodies of the same magnitude always oootain equal quantities of matter? LAW OF UNIVERSAL GRAVITATION. 259 tion of one pound for every 290 pounds : that Is, had the Earth no inoOon on her axis, all bodies on the equator would weigh one itco huruired and tigfUy-rUnth part more than they now do. Oft the contrary, If her diurnal morion were accelerated, the centriAifEai force would be proportionally increased, and the weight of bodies at ihe equator would be, in the same ratio, diminished. Should the Earth revolve upon its axis, willi a velocity which would make the day but&l minutes long, instead oflM hours, the centrifugal force would counterbalance that of gravity, and all bodies at Ihe equator would then be absolutely destitute of weight; and if the centrifugal force were further augmented, (ihe Earth reVol^ni( ia less time than 84 minutes,) gravitation would be completely overpoweredl and all Huids and loose substances near the equator would fly off from the surface. The weight of bodies, either upon the Earth, or on any other planet having amotion around its fxis. depends jointly upon the mass of the planet, uia Its diurnal velocitv./ A body weigHing one pound upon the equator of tli6 Earth, would weigh;'^if removed to the eqiuitor of the Sun, 27.9 lbs. Of Mei*- cury, 1.03 lbs. Of Venus, 0.98 lbs. Of the Moon, \ lb. Of Mars, 4 lb. Of Jupiter, 2.716 lbs. Of Saturn, 1.01 Ibo. ; i CHAPTER XXI. PRECESSION OP THE EQUINOXES-GBLiamTY OP THE ECUPTIC. Of all the motions which are going forward in tbe Solar System, there is none, which it is important to notice, more difficult to comprehend, or to explain, than the precession or THE EauiNoxES, as it is termed. The equinoxes, as we have learned, are the two opposite points in the Earth's orbit, where it cro'^es the equator. The first is in Aries ; the other, in Libra. By the preces' eion of the equinoxes is meant, that the intersection of thp equator with the ecliptic is not always in the same point: — in other words, that the Sun, in its apparent annual course, does not cross the equinoctial. Spring and Autumn, exactly in the same points, but every year a little behind those of the preceding year. This annual falling back of the equinoctical points, is call- ed by astronomers, with reference to the motion of the heavens, the Precession of the Equinoxes ; but it would bet- ter accord with fact as well as the apprehension of the learn- er, to call it, as it is, the Recession of the Equinoxes : for the equinoctial points do actually recede upon the ecliptic, at the rate of about 50V of a degree every year. It is the name Hmo ia the weight r\f bodies on the Earth's equator affected by its diurndtivtation ? What toouJd be the effect if the diurnal motion of the^ Earth were accelerated 1 WUa would be the consequence if the Earth revolved about its axis in 84 minutes, cf in ^w ttnie ? What are the equinoxes ? What is meant by the precession of the equiouxvs 1 by u It called prttestion ot ttic equinoxF*, and what would ha a better term) FRSCeSSION OF THE EaDINOZES, AC. 2G3 EqmitificiMd opiy, and not the position, of the equinoxes which remains permanent. Wherever the Sun crosses the equinoctial in the spring there is the vernal equinox ; and wherever he crosses it in the autumn there is the autumnal equinox, and these points are constantly moving to the west. Fig. 22. To render tliis subject fa- miliar, we will suppose two carriage roads, extehdiog fiaite around the Garth : one, representhig the equator, running due east and west ; and the uther» renreseoting the ecliptic, running nearly in the same direction as the former, yet so as to cross it wirh a small angle, (say of 23^^,) both at the point where we now stand, for in- stance, and in the nadir, exactly opposite ; let there also be another road, lo represent the prime meridi- an, running north and south, and cro8sin|f the first at right anzles, m the common point of intersection, as in the annexed figure. Let a carriage now start from tliis point of intersec- tion, not In the road leading directly east, but along that of the ecliptic, which leaves the former a little to the north, and let a person be placed to watch when the carriage com«a around again, after having made the circuit of the Earth, and see wlicther the carriage will cross the equinoctial road again precisely in the aam* track as when it left the goal. Though the person stood exactly in the former track, he need not fear being run over, for the carriage will cross the road 100 rods west of hitn, that is, 100 rods west of the meridian on which he stood. It is to be observed, thai 100 rods on the equator is equal to 50( seconds O! a degree. ir the carriage still continue to go around the Earth, it will, on completi'ag its second circuit, cross the equinoctial path 2U0 rods west of the meridian whence it first set out; on the third circuit, 300 rods west; on the fourth circuit, 400 rods, and so on, continually. After 71} circuits, the point of m- terseclion would be one degree west of its place at the commencement of the route. At this rate it would be easy to determine how many complete circuits the carriage must perform before this continual falling back of tho intersecting point would have retreated over every degree of the orbit, uptU it reached aealn the point from whence it first departed. The application of this illustration will be manifest, when we consider, further, that, The Sun revolves from one equinox to the same equincx again, in 365d. 5h. 48^ 47'^81. This constitutes the natu- ral, or tropical year^ because, in this period, one revolution of the seasons is exactly completed. But it is, mean- The equinoctial points are continually movinc : how, then, i* their position definei. CHve, at length, a familiar iUtutration by wMch thit tubject may be underttood. awppoee the mrrUtge eontintiea Us circuit around the earth, where would it erost the equinoctial the 9i2, 8^ H^ / ~~~^»v hi- ( ^ "^^ 1 t \ / ^ w \ ^ y 1 To explain this bj a figure ; Suppose the Sun to have been is conjunction with a &ced star at S, iov the first degree of Taurus, (the second sign of the ecliptic) 340 years bcfore'the birth of oar Saviour, or about the I7tb year of Alexander the Oreat ; then having made 2140 revolutions through the ecliptic, he would be found ajirain at the end of so many sidereal years at 8; but at the end of so many Julian yean^ he would be found at J, and at the end of so many tropical years, which would bring it down to the beginning of the (iresent century, he would be found at T, in the first degree of Aries, which las receded from S to T in that time by the precession of the equinoc* tial points Aries and Libra. The arc S T would oe equal to the amount of the precession (for precession we must still call it) of the equinox in 2140 years, at the rate of 50/' 23572 of a degree, or 20 minutes and 23 seconds of time annually, as above stated. From the constant retrogradation of the equinoctial points, and with them of all the signs of the ecliptic, it follows that the longitude of the stars must continually increase. The fame cause affects also their right ascension and declination. Hence, those stars which, in the infancy of astronomy were in the sign Aries, we now find in Taurus ; and those which were in Taurus, we now find in Gemini, and so on. Hence likewise it is, that the star which rose or set at any particu- lar time of the year, in the time of Hesiod, Eudoxus, Virgil, Pliny^ and others, by no means answers at this time to their descriptions. Explain this by a diagram. How does the «etregiadation of the equinoctial poiMs afieet the tongritude of tbe stars 1 Does the same cause extend to their right asemsbt VKldeclinatiooalso} HowtstbisrenderadapiMuvnt? 23 2p0 PRECESSION OF THE CQUINOXES, AC. Hesiod, In his Opera et Dies, lib. ii. rorse 185, aayi : When from tlie solstice sixty wiatnr days Ttieir turns have finisli'd, mark, with glitt'ring rays, Froru Ocean'a sacred flood, Arcturus rise. Then first to gild the dusky evening skies. • But Arcturus now rises acronycally ia latitude 37^ 45' N. the latitadv t liesiod, and nearly that of Richiuoad. in Virginia, about 100 days after th« winter solstice. Supposing Ilesiod to be correct, there is a difference of 4( days, arising from the precession of the equinoxes since the days of Hesiod Now as there is no record extant of the exact period of the world when thii poet flourished, letosisee to what result astronomy will lead us. As the Sun moves through about 39° of the ecliptic in 40 days, the wintei solstice, in the time of Hesiod, was in the 9th degree of Aquarius. Now es timatlug the prf^cession of the equinoxes at 50^" in a year ; we sliall have &0^'' : lyear: : 39° : 2794 years since the time of Hesiod; if we substract from this OUT present era, 1836, it will give 968 years before Christ. Ijempriere, in his Classical Dictionary, sa^s Hesiod lived 907 year^ before Christ See s similar calculation for the time of Thales. ^ age &ft. ^ The retrograde movement of the eqainoxes, and the an- nual extent of it, were determined hy comparing the longitude of the same stars, at different intervals of time. The most careful and unwearied attention was requisite in order to determine the cause and extent of this motion ; — a motion so very slow as scarcely to be perceived in an age, and oc- cupying not less than 25,000 years in a single revolution. It has not yet completed 0726 quarter of its first circuit in the heavens since the creation. Thus observation has not only determined the abso- lute motion of the equinoctial points, but measured its limit; it has also shown that this motion, like the causes which pro- duce it, is not uniform in itself: but that it is constantly ac- celerated by a slow arithmetical increase of V of a degree m 4,100 years. — A quantity wTiich, though totally inappre- ciable for short periods of time, becomes sensible after a lapse of ages. For example : The retrogradation of the equinoctial points is now greater by nearly Y' ^^^^ it was in the time of Hipparchus^ the^first who observed this mo- tion ; consequently, the mean tropical yeariss^r^cr now by about 12 seconds than it was then. For, since the retro- gradation of the equinoxes is now every year greater than It was then, the Sun has, each year, a space of nearly ^''• less to pass through in the ecliptic, in order to reach the plane ol the equator. Now the Sun is 12 seconds of time in p issing over ^" of space. At present, the equinoctial points move backwards^ or from east to west along the path of the ecliptic at the rate ot — _i - — - - — - . -.. , — - Mention an example. History does not enable us to Ax the precise age oif the xoortd in which Hesiod jCoturished; what light docs astronomy shed upon this gveiftion? By what means was the retrogradation of the ^uinoxes determined? "l^ by was it diffi- cu'.t to detennine the cause and extent of this motion? Not to specify particular cases, wnat has ofaservatioa at ienstfa determioed, with respect to the limit and uniformity of this hackward movement of the equinoctial points ? Give an exximple. Why should the tromeaJ 7««t, on this account, be shorter pow than it was then ) What ia the pnssont rata w motion or the equmoeUal points } r -m PRECE88I01I OF THE EClUIMOXEfl, *e. 267 I® in 7 Li years, or one whole sign, in 2140 years. Con- tinuing at this rate, thev will fall back through the whole of the 12 signs of the ecliptic in 25,680 years, and thus re- tarn to the sumeposition among the stars, as in the beginning. But in determining the period of a complete revolution of the equinoctial points, it must be borne in mind that the motion itself is continually increasing ; so that the last quar- ter of the revolution is accomplished several hundred years sooner than the first quarter. Making due allowance for this accelerated progress, the revolution of the equinoxes is com- pleted in 25,000 years ; or, more exactly, in 24,992 years. Were the motion of the equinoctial points uniform: that is, did they pass through equal portions of the ecliptic in equal times, they would accomplish their first quarter, or pass through the Jirst three signs of the ecliptic, in 6,250 years. But they are 6,575 years in passing through the first quar- ter ; about 218 years less in passing through the second quarter; 218 less in passing through the third, and so on. The immediate consequence of the precession of the equi- noxes, as we have already observed, is a continually pro- gressive increase of longitude in all the heavenly bodies. For the vernal equinox being the initial point of longitude, as well as of right ascension, a retreat of this point on the ecliptic tells upon the longitudes of all alike, whether at rest or in motion, and produces, so far as its amount extends, the appearance of a motion in longitude common to them all, a^ty the whole heavens had a slow rotation around the poles of the ecliptic in the long period above mentioned, similar to what they have in every twenty-four hours around the poles of the equinoctial. As the Sun loses one day in the year on the stars, by his direct motion in longitude ; so the equi- nox gains one day on them, in 25,000 years, by its retrograde motion. The cause of this inotion was unknown, until Newton proved that it was a necessary consequence of the rotation of the Earth, combined with its elliptical figure, and the un- equal attraction of the Sun and Moon on its polar and equa- torial regions. There being more matter about the Earth's equator than at the poles, the former is more strongly at- tracted than the latter, which causes a slight gyratory or In what time, continuinf; at the same ra\e, will they fiiH back through the twelve stgni of the ecliptic ? In determining the exact period of a complete revolution of the equinoctial Kints, what important circumBtaiite most be borne in mind ? Making due allowance fiir }ir accelerated progress, in what time is a revolution of the equinoxes completed? Is this motion as quick in the first quarter of their revolution as in the last? What is the titne and d^erence, of describing each quarter? What in the immediate consequence of the precession of the equinoxes upon the position of the heavenly bodies 7 Explain how this takes place. IIow does this resemble the annual loss of a sidereal day by the Sun ) What is toe cause of this motloo} 808 PRECESSION OF THB EQUlIfOXOS, *C wabbling motion of the poles of the Earth aronnd those of the ecliptic, like the pin of a top about its centre of motion, when it spins a little obliquely to the base. The precession of the equinoxes, thus explained, consists in a real motion of the pole of the heavens among the stars, in a small circle around the pole of the ecliptic as a ceatre, keeping constantly at its present distance of nearly 23i^ from it, in a direction from east to west, and with a progress so very slow as to require 25,000 years to complete the cir- cle. During this revolution it is evident that the pole w^ill Eoint successively to every part of the small circle in the eavens which it thus describes. Now this cannot happen without producing corresponding changes in the apparent diurnal motion of the sphere, and in the aspect which the heavens must present at remote periods of time. The effect of such a motion on the aspect of the hea- vens, is seen in the apparent approach of some stars and con- stellations to the celestial pole, and the recession of others The bright star of the Lesser Bear, which we call the pole star, has not always been, nor will always continue to be, our polar star. At the time of the construction of the ear- liest catalogues, this star was 12^ from the pole ; it is now only 1^ 34' from it, and it will approach to within half a degree of it ; after which it will again recede, and slowly give place to others, which will succeed it in its proximity to the pole. The pole, as above considered, fs to be understood, merely, as the vaiu taking point of the Earth's axis ; or that point in the concave sphere which is always opposite jthe terrestrial pole, and which consequently must move as that moves. " "f-- The precession of the stars in respect to the equinoxes, is less apparent the greater their distance from the ecliptic ; for whereas a star in the zodiac will appear to sweep the whole circumference of the heavens, in an equinoctial year, a star situated within the polar circle will describe only a very small circle in that period, and by so much the less, as It approaches the pole. The north pole of the earth being elevated 23^ 27^' towards the tropic of Cancer, the circumpolar stars will be successively, at the least distance from it, when their longitude is 3 signs, or 90*=*. The posi- Admittin^ this explanation, in what does the precession of the equinoxM really eoosisti To what point in the heavens will the pole of the Earth be directed, during the revolution i How must this aiU'ct the diurnal motion and aspect of the lieavens, in remote ages "* Wherein will the eilS;cts of such a motion be pcirticulariy visible? Give an instance. Whan you speak of the polb as in motion, ichat is to be understood by that term i In the prccessilhe change from taking place, is constant. Hence the Earth, which is so nicely poised on her centre, bows a In what li^t have we hitherto considered the great circles of the heavens 7 But what is thp fact } By what cause is the dispiaoement of the e<9ilnoetial, or the plane of tiie Earth's equator, effected } How is the displacement of the plane of tlie ecliptic ef^^ted? If the planetary attraction tends constantly to draw the planes of the equinoctial and ecliptic nearer torcther, what is to prevent them from comcidinr in one and the same plane ? How much is the distance or angle between them diminished every year ? What was the ohltquity qf the eclipjtc, or the qtiantUy of this angle, at the commencement S^f5f.?^'^"'«£!J?i"/2LL J^^^T^^Sif? diminution qf the obliquity svbject to any SJ tt£ (SSiauit^^ ^ ^''^ ^ ^ attraction of tfie Sun and Moot OBLiaUIlt or THB ECUPTIC. 271 little to the influence of the Moon, and rises again, alternate- ly, like the gentle oscillations of a balance. This curioas phenomenon, is called Nutation, In consequence of the yearly diminution of the obliquity of the ecliptic, the tropics are slowly and steadily approach- ing the equinoctial, at the rate of little more than three fourths of a second every year ; so that the Sun does not now come so far north of the equator in summer, nor de- cline so far south in winter, by nearly a degree, as it must have done at the creation. The most obvious effect of this diminution of the obliqui- ty of the ecliptic, is to equalize the length of our days and nights ; but it has an effect also to change the position of the stars near the tropics. Those which weie formerly situated north of the ecliptic, near the summer solstice, are now found to be still farther north, and farther from the plane of the ecliptic. On the contrary, those which, accord- mg to the testimony of the ancient astronomers, were situ- ated south of the ecliptic, near the summer solstice, have ap- proached this plane, insomuch that some are now either situated within it, or just on the north side of it. Similar changes have taken place with respect to those stars situ- ated near the winter solstice. All the stars, indeed, parti- cipate more or less in this motion, but less, in proportion to their proximity to the equinoctial. It is important, however, to observe, that this diminution will not always continue. A time will arrive when this motion, growing less and less, will at length entirely cease, and the obliquity will, apparently, remain constant for a time ; after which it will gradually increase again, and con- tinue to diverge by the same yearly increment as it before had dimiinished. This alternate decrease and increase will constitute an endless oscillation, comprehended between cer- tain fixed limits. Theory has not yet enabled us to deter- mine precisely what these limits are, but it may be demon- strated from the constitution of our globe, that such limits exist, and that they are very restricted, probably not exceed- ing 2^ 42'. If we consider the effect of this ever varying attribute in the system of the universe, it may be affirmed What resulCa fiom thto alternate and opposite influence? Bjr what tdcen doei tb« Earth «how her respect to this inflaence of the Momi 7 What is this pbenomeDon called } What is the consequence of the yearly diminution of the obliquity of the ecliptic in respect to the position of the troi>ica, and the declination of the Sun 7 What other obvious eftecti result from this diminution? How does it afiect the decUnation of the stars near the solstices 7 Do all the stars partake, more or less, in this motion 7 Will this dimmutioa ofthe obliquity always continue? What are the lifnita of its alternate variation ? What would be the consequence, in respect to the seasons, should the plane of the echrtic ent coincide with Uic puuie ofthe equator } 278 TBB TI0E8. that the plane of the ecliptic never has coincided with the plane of the equator, and never will coincide with it. Such a coincidence, could it happen^ would produce upon the Earth perpetual springs The method used by astronomers to determine the obli- quity of the ecliptic is, to take half the difference of (he greatest and least meridian altitudes of the Sun. The following table exhibits the mean obliquity of the ecliptic for every ten years during the present century.- z' A. 1800 23° 27' 51" .78 1860 230 27' 27'- .36 1810 23 27 50 .21 1780 23 27 22 .79 1820 23 27 45 .64 1880 23 27 18 .22 1830 23 27 41 .07 1890 23 27 13 .rV) 1840 23 27 36 .50 1900 23 27 9 .08 1850 23 27 31 .93 1910 23 27 4 .52 CHAPTER XXII. THE TIDES. The oceans, and all the seas, are observed to be incessant- ly agitate^ for certain periods of time, first from the east towards the west, and then again from the west towards the east. In this motion, which lasts about six hours, the sea gradually swelfs ; so that entering the mouths of pvers, it drives back the waters towards their source. After a con- tinual flow of six hours, the seas seem to rest for about a quarter of an hour; iliev then begin to ebb, or retire back again from west to east tor six hours more ; and the rivers again resume their natural courses. Then after a seem- ing pause of a quarter of an hour, the seas again begin to flow, as before, and thus alternately. This re&:ular alternate motion of the sea constitutes the tideSj of which there are two in something less than twenty-five hours. The ancients considered the ebbing and ftowing of the tides as one of the greatest mysteries in nature, and were utterly at a loss to account for them. Galileo and Descartes, and particularly Kepler, made some succesisful advances towards ascertaining the cause ; but Sir Isaac Newton was the first who clearly showed what were the chief agents in producing these motions. The cause of the tides, is the attraction of the Sun and Moon, but chiefly of the Moon, upon the waters of the y^ bat u the method used liy astronomers for determining the obliquity of the ecliptic f ¥r bat regiilar motion ia observed in the great Ixidjr of waters upon the aUibe ? la what Bnoda ol time is this alternate ebbing and flowing accomplished? What is it called) owwerethMt phenomena regarded by the ancientt 7 Who ateertained their true eaute ? What is the eanae of the tides ) THB TIDES. 273 ocean. In virtue of gravitation, the Moon, by her attrac- tion, draws, or raises the water towards her; bat because the power of attraction dimioisbes as the squares of the dis- tance increase, the waters on the opposite side of the Earth, are not so much attracted as they are on the side nearest the Moon. That the Moon, says Sir John Herschel, sliould, by her attraction, beu) op the waters of the ocean under her, seems to most persons very natural; but that the same cause should, at the same time, heap them up on the oppo- site side, seems, to many, palpably absurd. Yet nothing is more true, nor indeed more evident, when we consider that it is not by her whole attraction, bat by the differences of her attractions at the opposite surfaces and at the centre, that tlie waters are raised. That the tides are dependent upon some Icnown and determinate laws, is evident from the exact time of high water being previously given in every ephemeris, and in many of the common ahnanaclcs. The Moon comes every day later to the meridian than on the day preceding, and her exact rime is known by calculation; and the tides in any and evei^ place, will be found to follow the same rule; happening exactly -m much later every day as the Moon comes later to the meridian. From rriia exact conformity to the motions of the Moon, we are induced to loolc to >ier aa the cause ; and to infer that these phenomena are occasioned principsily by the Bloon's attraction. THE TIDES. Fig. 21 Fig. 25. Fig. 2& If the Earth were at rest, and there were no attractive in- fluence from either the Sun or Moon, it is obvious from the Principles of gravitation, that the waters in the ocean would e truly spherical; (as represented by Fig. 24;) but daily observation proves that they are in a state of continual agi- tation. If the Earth and Moon were without motion, and the Earth covered all over with water, the attraction of the Moon would raise it up in a heap, in that part of the ocean to which the Moon is vertical, as in Figure 25, and there it would, prob- How does the attraction of the Sun and Moon produee tides upon both sides of the eaitliatthe same time? What is 8lr John HenehePt rentark upon thU theory? Boie it it known that the, tidee are governed In/ any aacertuined law 7 What coinci- 'dence ie observed between the fneridian pcueage qf the Moon, and the time of high water 7 What eonctuelon may toe derive from this coincidence 7 If the Earth were at rcMt, and under no influence firom the attractiarr of the Earth which ia at any time turned from the Moon^ being about 000 niiles farther from the centre of gravity, than the side next tlie Moon, would have a greater centrifugal force than the aide next her. At the Earth's centre, the centrifugal forco will balance tiie attractive force ; therefore as much water is thrown o^ by the cenirifogal force on the side which is turned from the Moon, as is raised on the side next her by her attraction. From the universal law, that the force of gravity dimin- ishes as the square of the distance increases, it results^ that the attractive power of the Moon decreases in intensity at every step of the descent from the zenith to the nadir ; and consequently that the waters on the zenith, being more at- tracted by the Moon than the Earth is at its centre, move faster towards the Moon than the Earth's centre does: And as the centre of the Earth mtxres faster towards the Moon than the waters about the nadir do, the waters will be, as it were, left behind, and thus, with respect to the centre, they will be raised. The reason why the Earth and waters of oar globe do not seem to be af* fected emially by the Moon's attraction, is, that the earthy snbstance of the glube, being nrmly united, does not yield to any difference of the Moon's at* tractive force; insomuch that its upper and lower surface must move equally fast towards the Moon ; whereas the waters, cohering together but very light* Ij, yield to the different degrees of the Moon's attractive force, at different distances from her. The length of a lunar day, that is, of the interval from one meridian passage of the Moon to another, being, at a mean rate, 24 hours, 48 minutes and 44 seconds, the inter- val between the flux and the reflux of the sea is not, at a mean rate, precisely six hours, but twelve minutes and eleven seconds more, so that the time of high water does not happen at the same hour, but is about 49 minutes later every day. Tne Earth revolves on its axis in about twenty-four hours j if the Moon, therefore, were stationary, the same part of our globe would return beneath it, and there would be two tides every twenty-four hours ; but while the Earth is turning once upon its axis, the Moon has gone forward 13° in her orbit— which takes forty-nine minutes more before the same meri- dian is brought again directly under the Moon. And hence every succeeding day the time of high water will be forty- nine minutes later than the preceding. For example :— Suppose at anv place it be high water at 3 o'clock !o the afternoon, upon the day of new Moon ; the followins day it will be high water alK>ut49 minutes after 3 ; the day after, about 38 mmutes after 4; and so on, How is this phenomenon otherwiie explained, by the laws of gravity, merely ? Are ths Earth and watera qft?ie globe affecteti equally, by the Moon's attraction t Why not I What is the avereoe interval between the flux and reflux of the sea 1 What is the length ofa lunar day, and of the interval of the flux and reflux of the seal How L« this daily 'etaid4t|on of tlie tides aeoountcd for 1 Qive an esnmpU 'i ^ 276 THE TIOE& mi the next new Moon. The exact dailf mean retardation of the tides is that determined : Tlie mean motion of the Moon, in a aolar daj. ia 13^.17639639 The mean motion of the Son, in a solar day, m .98664722 Now, as 150 ia to 60 minatea, ao ia 120. 19074917 to 48* 44". Ii is obvious that the attraction of the Sun must produce upon the waters of the ocean a like effect to that of the Moon, though in a less degree ; for the great mass of the Sun is more than compensated by its immense distance. Nevertheless, its effect is considerable, and it can be shown, that the heigfit of the solar tide is to the height of the lunar tide as 2 to 5. Hence the tides, though constant, are not equal. They are greatest when the Moon is in ccoijUQction with, or in opposition to, the Sun, and least wheii^ in quad • rature. For in the former cAse, the Sun and Modn set to- gether, and the tide will equal the sum of the«olar and lunar tides, and in the latter they act against each other, and the tide will be the difference. , . / The former are called Spring TiJes; the latter, Neap Tides. The spring tides are highest, when the Sun and Moon are near the equator, and the Moon at her least distance from the Earth, The neap tides are lowest, when the Moon in her first and second quarters is at her greatest distance from the Earth. The general theory of the tides is this: When the Moon is nearest the Earth, her attraction is-strong* est, and the tides are the highest ; when she is farthest from the Earth, her attraction is least, and the tides are the lowest. From the above theory, it might be supposed that the tidea would be the highest wlien the Moon was on the meridian. But it is found that in open seas, where the water flows freely, the Moon has generally passed the north or south meridian about three hours, when it is high water. The reason is, that the force by which the Moon raises the tide continues to act, and consequently the waters continue to rise, after she has passed the meridian. For the same reason, the highest tides, which are pro- duced by the conjunction and opposition of the Sun and Moon, do not happen on the days of the full and change ; neither do the lowest tides happen on the days of their quadratures. — But the greatest spring tides commonly hap- Are the tides umfonnlyhieh? When, and on what aeoount do titer differ? What ara dxise extreme tides called? When are the spring tidea highest? When are the neap tides lowest 7 What is the seperal theorjr upon this suhje^? Does it oeoeesarily rmS gwn this Aeory. tluit ^ ude is highest when the Moon is on the meridian ? What leaiwa ■ assigned for this 7 What similar ^ct is accounted Ibr upon the same principlcl THE TID£S. 877 pen 1} days aflnr the new and full Moons ; and the least neaip tid^^ 1} days after the first and third quarters. The Sun and Moon, bv reason of the elliptical form of their orbits, are al ternately nearer to and farther from the Earth, than their mean distances. In consequence of this, the efficacy of the Sun will fluctuate betAveen the ex* t rentes 19 and 21, taking 20 for its mean value, and between 43 and 59 for that of the Moon. Taking into account this cause of difference, the highest spring tide will be to the lowest neap as 59-f 21 is to 43—19, or as 80 to 24, or 10 to 3. The relative n^an influence is as 61 to 20^ or as 5 to S^ nearly. — IhrscheVs Astr. p. 339. Though the tides, in open seas^ are at the highest about three hours after the Moon has passed the meridian, yet the waters in their passage through shoals and channels, and by striking against capes and headlands, are so retarded that, to dijSerent places, the tides happen at all distances of the Moon from the meridian ; consequently at all hours of the lunar day. In small collections of water, the Moon acts at the same time on every part 5 diminishing the gravity of the whole mass. On this account there are no sensible tides in lakes, they being generally so small that when the Moon is verti- cal, it attracts every part alike ; and by rendering all the waters equally light, no part of them can be raised higher than another. The Mediterranean and Baltic Seas have very small elevations, partly for this reason, and partly be- cause the inlets by which they communicate with the ocean are so narrow, that they cannot, in so short a time, either receive or discharge enough, sensibly to raise or sink their surfaces. , Of all the causes of difference in the height of tides at different places, by far the greatest is local situation. In wide-mouthed rivers, opening in the direction of the stream of the tides, and whose channels are growing gradually narrower, the water is accumulated by the contracting banks, until in some instances it rises to the height of 20, 30, and even 50 feet. Air being lighter than water, and the surface of the at- mosphere being nearer to the Moon than the surface of the sea, it cannot be doubted but that the Moon raises much higher tides in the atmosphere than in the sea. According tn Sir John Herschel these tides are, by very delicate ol^ *ervalions, rendered not only sensible, \^\it measurable. Upon the supposition that the waters on the surface of the Moon are of What is tht comparative /orC6 cfthe solar and lunar attraction upon the Earth t To wliat u owing the great difl^renoe in the time of high water at places lying under tfa* same meridian? Why are there no tides upon lakes, and small cc^ectioiu of water? To what cauae, more than to all otben, is the different height of tides owing? EroJani this. Is it probible that tlie Moon exerts any iofluenoe of attmctkHi on the atmpspl^l ^hy h it probable ? Are the atmoapheric tidss safflcieatly lentible to be aptseeiatebl 24 278 THE SEASONS. liie nme tpecific gravity as oar owOi we miglit easily determine the helgiit to which the Earth would raise a lunar tide, by the l^nown priuctpl'^, that tba ■ttraction of one of these bodies on the otlier's surface is directly as ita quantity of matter, and inveraely as its diameter. By mailing the calculation! sre shall find the attractive power of the Earth upon the Moon to be 21.777 times greater than that of the Moon upon the Earth. CHAPTER XXIII. THE SEASONS — DIFFEAENT LENGTHS OF THE DAYS AND NIGHTS. The vicissitudes of the seasons and the unequal lengths of the days and nights, are occasioned by the annual revo- lution of the Earth around the Sun, with its axis inclined to the plane of its orbit. The temperature of any part of the Earth's surface depends mainly, if not entirely, upon its exposure to the Sun's rays. Whenever the Sun is above the horizon of any place, that place \s receiving heat; when the Sun is below ttie horizon it is parting with it, by a process which is called radiation. The quantities of heat thus received and imparted in the course of the year, must balance each other at every place, or the equilibrium of temperature would not be supported. Whenever, then, the Sun remains more than twelve hours above the horizon of any place, and less beneath, the gen- eral temperature of that place will be aboce the mean state; when the reverse takes place, the temperature, for the same leason, will be below the mean state. Now the continuance of the Sun above the horizon of any place, depends entirely upon his declination, or altitude at noon. About the 20ia of March, when the Sun is in the vernal equinox, and con- sequently has no declination, he rises at six in the morning and sets at six in the evening; the day and night are then equal, and as the Sun continues as long above our horizon as below it, his influence must be nearly the same at the same latitudes, in both hemispheres. From the 20th of March to the 21st of June, the days grow longer, and the nights shorter, in the northern hemis- phere the temperature increases, and we pass from spring, to mid-summer ; while the reverse of this takes place in the How much greeter U the attractive potoer qfthe Earth upon the Moon, than that of the Moon upon the Earth ? What occasions the vicissitudes of the seasons, and the an- eciual lengths of tiie days and ni^tsl Upon what does the tempeiaturo at diflormt pbees depend 7 Under what cireuinstances do the same places change their tempefature ? An the quantities of heat, recaved and imparted, eveiy yoar, always eqaal at the same plaew > Why IS It so 1 y^ hen is the temperature of a place above, and when is it below its men ^^l Si°" Y^^wJ^ the oonnnwinoe of the Sun above the horizon of any pteoeTS SS?*'' )?^»t5»t*«S"n ".*«»« «tw^our horizon as below it? Durink wlS SSooTr the year is the temperatun moruasipc) -«"»" ••» vmi 3G5 6 56 II the winter solstice 1834, ) Mean or average length of the tropical year, 365 5 48 4S The north pole of the Earth is denominated the elevated pole, because it is always about 23}^ above a perpendicular to the plane of the equator, and the south pole is denomina- ted the depressed pole, because it is about the same distance below such perpendicular. As the Sun cannot shine on more than one half the Earth's surface at a time^ it is plain, that whenlhe Earth is moving through that portion of its orbit which lies above the Sun, the elevated pole is in the dark. This requires six months, that is, until the Earth arrives at the equinox, when the elevated pole emerges into the light, and the depressed pole is turned away from the Sun for tne same period. Consequently, there are six months day and six months night, alternately, at the poles. When the Sun appears to us to be in one part of the eclip- tic, the Earth, as seen from the Sun, appears in the point di- ametrical! jr opposite. Thus, when the Sun appears in the vernal equinox at the first point of Aries, the Earth is actu- ally in the opposite equinox at Libra. The days and nights are then equal all over the world. As the Sun appears to move up from the vernal equinox o the summer solstice, the Earth actuallv moves from the lutumnal equinox down to the winter solstice. The days tow lengthen in the northern hemisphere, and shorten in tne outhern. The Sun is now over the north pole, where it is nid-day, and opposite the south pole, where it is mid-night. Why IB the north pole denominated the elevated pole 7 Why is the south pole denomi- «ted the deprcMed pole 1 Why are there sue months day and sjx month night, alternately. 4 the polos ? )* "lat isdwaj^s tlw relative posiUoa of the Sun and Earth in the eclipti?? *yo an example. When do the days iM^ northern hemisphere, and sliorten in «e southern 1 Wli»n u it mid-dvy at the north pole, and midnight at the south ? THE SEA801I8» 281 As the San descends from the sammer solstice towards the autamnal equinox, the Earth ascends from the winter solstice towards the vernal equinox. The summer days in the northern hemisphere having waxed shorter and shorter, now become again of equal length in both hemispheres. While the Sun appears to move from the autumnal equi- nox down to the winter solstice, the Earth passes up from the vernal equinox to the summer solstice ; the south pole comes into the light, the winter days continually shorten in the northern hemisphere, and the summer days as regularly iu crease in length in the southern hemisphere. While the Sun appears again to ascend from its winter, solstice to the vernal equinox, the Earth descends frona^the summer solstice to the autumnal equinox. The summer days now shorten in th^ southern hemisphere, and the win- ter days lengthen in the northern hemisphere. When the Sun passes the vernal equmox, it rises to the arctic or elevated pole, and sets to the antarctic pole. When the Sun arrives at the summer solstice, it is noon at the north pole, and midnight at the south pole. When the Sun passes the autumnal equinox, it sets to the north pole, and rises to the south pole. When the Sun arrives at the win- ter solstice, it is midnight at the north pole, and noon at the south pole ; and when the Sun comes again to the vernal equinox, it closes the day at the south pole, and lights up the morning at the north pole. There would, therefore, be 186J days during which the €nn would not set at the north pole, and an equal time du- ring which he would not rise at the south pole; and ITSiJ- days in which he would not set at the south pole, nor rise at the north pole. At the arctic circle, 23° 27^' from the pole, the longest day is 24 hours, and goes on increasing as you approach the pole. In latitude 67° 18' it is 30 days; in lat. 69° 30' it is 60 days. &c. (See Table XII.) The same takes place be- tween the antarctic circle and the south pole, with the ex- ception, that the day in the same latitude south is a little shorter, since the Sun is not so long south of the equator, as at the north of it. In this estimate no account is taken of the refraction of the atmosphere, which, as we shall When do the gammer days in the northern hemiaphore grow shorter and shorter 7 When do they become of equal length in both hemispheres 7 When do the winter dars shorten tn^he nortliem hemisphere, and t)ie summer days lengthen in the southern? When do the summer days shorten in the southern hemispherei and the winter days lengthen inthe northern? When does the sun rise to the nurth polei and set to the south? When is it noon at the north pole, and mid-night at the south pole? When does the Sun set at the north pole, and rise to the south 7 When is it mid-night at the north polf>. and noon at the ■outh 7 What is the length of the day at the north pole 7 What at *h» aouth polei At th(> arctic circle 7 Between the antarctic sircle and the pole ^ 24* i'ta TBE SEASONS. ii«e hereaftei, increases the length of the day, by makmc the San appear more elevated above the horizon ths^ it real- ly is. K THE 8EA80X8 — UNEftUAL LENGTHS OF DATS AND NIGHTS. K'^m The above cut represents the inclination of the Eartli's axis to its orbit In every one of the twelve signs of the ecliptic, and consequently for each month in Ihu year. Tiie Sun enters the sign Aries,^ or the vernal equinox, on the 20tii of March, when the Earth's axis inclines nritlier towards the San, nor from it, but sideways Xo It; so that the Sun then eliines equally upon tho Earth from pole to pole, and the days and nights are every where equal. This is the beginning of the astronomical year ; it is also the beginning of day at the north pole, which is just coniing into light, and the end of day at the south pole, which is jusf going into darliness. By the Earth's orbitual progress, tiie Sun appears to enter the second sign, Taurus, on the 20th of April, when the north polo, iV, has sensibly advanced into the light, while the south pole, S, has been declining from it ; whereby the days become longer than die nights in the Northern Hemisphere, and shorter in the Southern. On the 21st of May, the Sun appears to enter the sign Gemini^ when the north pole, N^ has advanced considerably further into the liglit, while the south pole, S^ has proportionally declined from it ; the summer days are now waxing longer in the Northern Hemisphere, and the nights shorter. The 2Ut of June, when the San enters the sign Cancer, is tiie first day of summer, in the astronomical year, and the longest day in the Northern Hemis* Eliere. The north pole now has its greatest inclination to the Sun, the ght of whicli, as is shown by the boundary of light and darkness, in the figure, extend* to the utmost verge of the Arctic Circle; the whole of which is incUided m rhe enlightened hemisphere of the Earth, and enjoys, at this f^^\^^''^^?!S:f^Ji^^]^^i^^J^PS'^^^^^ revolution of the Earth on its axis. The whole of the Northern Frigid Zone is now in the circle of perpetual iUtt- mination. *^ *^ HARVEST HOOM» 9(88 lu the Nortliem Hemisphere, which had arriYcd at its majdmnm, begins gMdually to decrease. On the 23d of August, the Sua enters the aign FSr^a, increasing the appearances mentioned ial^eo^ On tlie 23d or September, the San enters Libra, the first of the autamnal itigns, when the Earth's axis, having the same inclination as it* had in the op- posite sign, ArieSj is turned neither /rom the Sun, nor tou>ardb it, but oblique ly to it, so tiiat the Son again now shines equally upon the whoto of the Euth'i surface from pole to pole. The days and niglits are once more of equal length throughout the world. On the 23d of October, the Sun enters the sign Snrpio ; the days visiUy decrease in length in the Northern Hemisphere, and increase in the Soutli- ern. On the 22d of November, the Sun enters the ngn SagiUariua, the last of the autumnal signs, at which time the boundury of light and darkness is at a considerable distance from the north pole, while the south pole lias pn>« poriionally advanced into the light ; the length of the day continues to increase in the Southern Hemisphere, and to decrease in the Northern. On ttie 21st of December, which is the period of the winter solstice, the Sun enters the Kign Capricorn. At this time, the north pc^e of the Earth's ajLis is turned from the Sun, into perpetual darlcness; while the south pole, in its turn, is brought into the light of the Sun, whereby the whole Antaretie region comes into the circle of perpetual illumination. It is now that the Southern Hemisphere enjoys all those advantages with which the Northern Hemisphere was iavoored on the 21st of June; while the Northern Hemis- phere, in its turn, undergoes the dreariness of winter, with short days end long nights. CHAPTER XXIV. HARVEST MOON — HORIZONTAL MOON. The daily progress of the Moon in her orbit, from west to east, causes her to rise^ at a mean rate, 48 minutes and 44 seconds later every day than on the preceding. But in places of considerable latitude^ a remarkable deviation from this rule takes place, especially about the time of harvest J when the full Moon rises to us for several nights together, only from 18 to 25 minutes later in one day, than on that immediately preceding. From the benefit which her light affords, in lengthening out the day, when the hus- bandmen are gathering in the fruits of the Earth, the full moon. Under these circumstances, has acquired the name of Harvest Moon, It is believed that this fact was observed by persons engaged in agricaltursk at a mucii earlier period than that in which it was noticed by astronomers Tlie former ascribed it to the soodness of the Deity ; not doubting but that he had so ordered it for their advantage. About the equator, the Moon rises throughout the Tear with nearly the equal intervals of 48^ minutes ; and tnere the harvest moon is unknown. What is the mean difieienoe of time in the daily rising of the Moon ? Under what eir- eujnstances is there a material deviati^m fiwm this rale? Whence «» r^ngoT fiBwresI Uioon 1 By wham was thia phenomenon finit obeervedt ontf to what ate (MV aftrvuf U? Why w the Harvest Moon nnknown at the equator I 284 HARVEST MOON. At the polar circles, the autumDal full Moon, from her first to her third quarter, rises as the Sun sets ; and at the poles, where the Sun is absent during one half of the year, the winter full Moons, from the first to the third quarter, shine constantly without setting. Dy this, it is not meant t)ut the Moon e The parts or signs of the ecliptic which rise with the rmallest angles, set with the greatest ; and those which rise with the greatest, set with the least. And whenever this angle is least, a greater portion of the ecliptic rises in equal times than when the angle is l arger. Therefore, when the /UJ Wtneant afUie mrtlAcUU rt^JivuiJ. ^^*^ '^^ ^** phenomenon be exemptt- SSiprSSSn? »rX?22 /Ai/p^^%ft.V^^'* **''^ l^tftheectiptietn md why is it adopted? To wh£ ii^i^^S^KSk! S^f?^"^ ^^'^^ *• «?' "^ littitiidB.. owinff 7 'Give «n fnmnUli K&STOiJ?J&'^Vj£ *"?% "«*»'• *° ^i«»«l with Um ■mailest angles, and Um eontrury ' ^ "*"* **"* ecliptic set, which rise HAKV£ST MOON. 335 Moon is in those signs which rise or set with the smidiest angles, she rises or sets with the least difference of time ; but when she is in those signs which rise or set with the greatest angles, she rises or sets with the greatest differ- ence of time. Let ihe globe, for example, be rectified to the latitude of New York, 40^42' 40", with Cancer on the mertdiao, and Libra rising in the east m tliis position, tlie ecliptic has a high eievationj making an angle with the ho- rizon of 72io. But let the glpbe be turned half round on hs axis, till Capricorn conies to the meridian, and Aries rises in the east, then the ecliptic will have a low elevation above the horizon, making an angle with it of only 25*°. This angle is 47° less than the former angle, and ts equal to the distance between the tropics. In northern latitudes, the smallest angle made by tl^e ecliptic and horizon, is when Aries rises ; at which time Libra sets ; the greatest is, when Libra rises and Aries sets. The ecliptic rises fastest about Aries, and slowest about Libra. Though Pisces and Aries make an angle of only 25^-*^ with the horizon when they rise, to those who Jive in the latitude of New York, yet the same signs, when they set, make an angle of 72 j^^. The daily difference of the Moon's rising, when in these signs, is, in New England, about 22 minutes ; but when she is in the opposite signs, Virgo and Libra, the daily difference of her rising is al- most four times as great, being about one hour and a quarter. As the Moon can never be full but when she is opposite to the Sun, and the Sun is never in Virgo or Libra except in our autumnal months, September and October, it is evident that the Moon is never full m the opposite signs, Pisces and Aries, except in those two months. We can therefore have only two full Moons in a year, which rise, for a week togeth- er, very near the time oi sun-set. — The former of these is called the Harvest Moon, and the latter, the Hunter's Moon, Although there can be but two full Moons in the year that rise with so little variation of time, yet the phenomenon of the Moon's rising for a week together so nearly at the same time, occurs every month, in some part of her course or the other. In Winter^ the signs Pisces and Aries rise about noon ; hence the rising of Che Moon is not then regarded nor perceived. In Spring, these signs rise with ihe Sun, because he is then In them ; and as the Moon changes while passing throuzh the same sign with the Sun, it must then be tfie change, and hence invisible. What results from this in regard to the Moon 7 Hofo num tMt be tttuttrated on Os globe i In northern latitudeB, what signs rise and set with the least angles ? Wm^^ v>w the greatest? What parts of the ecliptic rise fittest, and wliich slowest 7 Give an ex- am{3e. What is the daily difference of the Moon's ripina and Mtfing, in tfaeae Ufns. m the laUtade of New York ) How many full Moons in a year, wliicli nsc witoso utUe dlT- farenco of time ? Why are not these phenomena obierped in the »ame tigne, tn wm (cr, Springi and Summer f 386 HORIZONTAL MOOR. lu Summery they rise about midnight, when the Moon is in her thifxidi> an, than they do in the horizon, because they are then actually nearer the place of the spectator^ by the whole semi-diameter of the Earth. Exjdain why there ia no Harvest Moon at the equator. The farther any place is frani the equator, how is the angle between the ecliptic and tlie horizon, uhen Pisce* nnd Ariea rise? Do the Harvest Moons happen as regularly, and in tlte same months, on the wouth side of the equator, as on the north f Why does not the full Moon me in summer, nor set in winter, to the inhabitanU of the polar circles 7 Acconiinv to >J>e ordinai7 laws of vision, how ought tho magnitudes of the Sun and Moon to appear, wlKn they ate near- est tlM9 honzon 7 WhHt is the fact? How much larger does tlie Moon appear to the naked eye, when in the horizon, than when at the altitude of thirty or forty degreeel Wner«, in reality, do the Stm and Moon ntbtend the Utrget angle ? Why UU—f BEFRACnON. 287 This apparent increase of magnitude in the horizontal Moon, is chiefly an optical illusion, produced by the concay- ity of the heavens appearing to the eye to be a less portion of a spherical surface than a hemisphere. The eye is ac- customed to estimate the distance between any two objects in the heavens by the quantity of 'sky that appears to lie be- tween them ; as upon the Earth we estimate it by the quan- tity of ground that lies between them. Now when the Sun or Moon is just emerging above the eastern horizon, or sinking beneath the western, the distance of the intervening landscape over which they are seen, contributes, together with the refraction of the atmosphere, to exaggerate our estimate of their real magnitudes. CHAPTER XXV. REPRACTION — TWILIGHT. The rays of light in passing out of one medium into ano- ther of a different density, deviate from a straight course $ and if the density of the latter medium continually increase, the rays of light in passing through it, will deviate more ana more irom a right line towards a curve, in passing to the eye of an observer. From this cause a]l the heavenly bodies, except when in the zenith, appear higher than they really are. This bending of the rays of light, giving to the heaven- ly bodies an apparent elevation above their true places, is called Refraction. It is in consequence of the refracting power of the atmos* phere that all heavenly bodies are seen for a short time 6e- fore they rise in the horizon, and also after they have sunk below it. At some periods of the year the Sun appears 6 minutes longer, morning and evening, and about 3^ minutes longer every day, at a mean rale, than he would do were there no refraction. The average amount of refraction for an object half way between the horizon and the zenith, i» at an apparent altitude of 45^, is but one sixtieth of a degree, a quantity hardly sensible to the naked eye; but at the visi- ble horizon it amounts to 33' of a degr ee, which is rather How ia the apparent increaae of magnitude in the horixontai Mood, accounted ftrl How are the rays of liffht aflected in passing out of one medium into another, of a difle^ ' ? How, if the density of the latter medium eoiitmnaUyincrease 7 What a*; ent density ? How, if the density of the latter medium eoiiunnatiy mcrease? w mi aff; tiomimicai phenomenon resulto from this cause? "^ hat is this bendmg of the rayiqi of refraction for an object half way between tnebocizon} iSB RCFRACTIOIf. more than the greatest apparent diameter of either ( \e Sun ur the Moon. Hence it follows, that when we see the lower edf : of the Sun or Moon just apparently resting on the horiz ti, their whole disc is in reality below it. and would be entuely out of sight and concealed by the convexity of the Eart) » but for the landing, which the rays of light have undergon in their passage through the air to the observer's eye. The foUowinfi^ general notions of its amount, and law of variations, should be borne in mind : 1. In the zenith there is no refraction ; a celestial object, situated directly over head, is seen in its true position, as if there were no atmosphere. 2. In descending from the zenith to the horizon, the refrac- tion continually increases ; objects near the horizon appear- ing more elevated by it than those of a higher altitude. 3. The rate of its increase is nearly in proporiion to the apparent angular distance of the object irom the zenith. But this rule, which is not far from the truth, at moderate zenith distances, ceases to give correct results in the vicinity of the horizon, where the law becomes much more compli- cated in its expression. Hie effects of refiraction must be fiuniliar to erery person who has seen a walking stick partially plunged into a river, or other collection of water. White the stick is held upright, it appears straight, as usual, i>ecaose there is uo refmctioa in this position ; but if it be ever so little inclined, the re* fraction takes place, and the stick appears bent ; if the inclination be in* creased, the refraction is also increased. Another easy and familiar illustration of the effect of refraction may be thus, obtained : — Put any small object, as a piece of money, into an empty basin, as near the centre as possible, and retire to such a distance as just to lose sight of the object. Let an assistant then pour water in the basin, and th« object will soon u^ar. Retire again till it is no longer seen ; let more water be added, and it will again appear. The experiment may be re- peated tin the basin is full. The edge of the basin may be supposed to represent the horizon; the water, the atmosphere ; and the piece of money, the Sun, or other object which is thus made to uppear by the power of re- fraction, when otherwise it would be invisible. It follows from this, that one obvious effect of refraction must be to shorten the duration of night and darkness, by prolonging the apparent stay of the Sun and Moon above the horizon. But even after they appear to have set, the in- fluence of the atmosjihere still continues to send us a portion >f their light ; not, indeed, by direct transmission, but by reflection : — for as long as the Sun continues to illuminate WhAi inteiesting Su^ lewilt from this tnitii) What is the firat seoeral law of atnos- pbeiiejnfiaction} Whatis the second general kw 7 What is the third? Mention • JtanUtar inaiance of refraction often 9un in toater. Mention mmefianiHar esperi- fnent.to ittustrate refractipn^ and thow ita application to cetrtmonty 7 How dost tfate iirinoiple a^ct the doratioQ of nocturnal daifenesa ) By what prioeiple is it tint tkt •toosplierBtendsusaportionof the solar light, for a coosiderable time S-foret^^| OMs, and aderit ba« let) ^ REPtAOnON. any portion of the atmosphere which is above the horizon, the light from this portion is reflected to the Earth, and it is this that causes twilight. In the morning, when the Sun arrives at 18° below the horizon, his rays pass over our heads into the higher region of the atmosphere, and are thence reflected^ or as it were, bent clown to the Earth. The day is then said to dawn, and the light gradually increases until the Sun appears above the horizon : this is called Morning' Twilight, or Aurora, which the heathens personified as a goddess. They assigned to her the office of opening the Gates of the East, to intro- duce the chariot of Apollo or Phabus, In the eveningj after sunset, the rays of the Sun continue to illuminate the atmosphere, till he sinks 18^ below the horizon, and a similar effect, called the Evening Twilight^ is produced, only in aft inverse progression, for the twilight ncfw gradually becomes fainter till it is lost in dark night. The quantity of reflection and the duration of twilight are much influenced by the changes which are perpetually tak- ing place with respect to the heat and cold, the dryness or moisture, &c. of the atmosphere. The height of the atmos- phere, also, has an influence in determining the duration of twilight : Thus in winter, when the air is condensed with cold, and the atmosphere upon that account lower, the twi- light will he shorter ; and in summer, when the limits of the atmosphere are extended by the rarefaction and dilation of the air of which it consists, the duration of the twilight will be longer. And for the same reason, the morning twilight, (the air being at that time condensed and contracted by the cold of the preceding night,) will be shorter than the even- ing twilight, when the air is more dilated and expanded. It is entirely owing to the reflecting power of the atmos- phere that the heavens appear oright in the day time. For without such a power, only that part of the heavens would be luminous in which the Sun is placed ; and, if we should turn our backs to the Sun, the whole heavens would appear as dark as in the night, and the stars, even at noon day, would be seen as clear as in the nocturnal sky. In regions of the Earth situated towards the poles, the Sun, during theii summer months, is never more than 18® below the horizon ; consequently their twilight continues What is TiiflHght 7 How is it occasioned ? How is the Evening Twilight produced I 97 wliat are the quantity of reflection, and the duration of twilight, considerably infill' enoed? Why is twilight shorter in winter? Why longer in summer 1 Why is the mom* ing twilight shor'er than tlie ^vening twih*ght? To what is it entirely, omng, tfaattht heavens- appear bright in the d^y time 7 How wtould the heavens agoear, if it were not Cur this power 7 What ara the duration and advantages of twilight inoigh l^titmias ) 25 too AUROBA B< REALI9. dorins: the whole night. The same cause has a tendency to diminish the gloom of the long polar nights ; for as far north as in lat. 84° 32^' the Sun even when at the winter solstice approaches to within 18° of the horizon, and affords a short twilight once in 24 hours, and the pole itself is left in total darkness not more than 80 days. There is still another cause which has a tendency to di- minish the length of the polar nights, the extraordinary refraction occasioned by the extreme density of the air in those regions. This is so great, as to bring the Sun above the horizon some days before it should appear, according to calculation. • A remarkable phenomenon of this kind was observed by the Dutcti navi- gators who wintered in Nova Zembla, In the year 1596. After enduring a continual night of tfaree months, they were agreeably surprised to find that the Sun began to rise attcnteen days sooner than accor diner to computation! The observed altitude of the pole, at the place, (says Dr. Smith,) being only T6°, It is impossible to account for (he phenomenon, otherwise, than by sup- posing an extraordinary refraction of the Sun's rays. Kepler computes that the Sun was almost 6^ below the horizon when he first appeared ; and con- sequently, that the refraction of his rays was about 10 times greater than with us. CHAPTER XXVI. AURORA BOREALId. The sublime and beautiful phenomena presented by the Aurora Borealis, or Northern Lights, as they are called, have been in all ages a source of admiration and wonder alike to the peasant and the philosopher. In the regions of the north, they are regarded by the ignorant with supersti- tious dread, as harbingers of evil ; while all agree in placing them among the unexplained wonders of nature. These lights, or meteoric coruscations, are more brilliant in the arctic regions, appearing mostly in the winter season and in frostjr weather. They commonly appear at twilight near the horizon, and sometimes continue in that state for several hours without any sensible motion; after which they send forth streams of stronger light, shooting with great velocity up to the zenith, emulating, not unfrequently, the lightning in vividness, and the rainbow in colouring ; and again, silently rising in a compact majestic arch of steady — — - — — — — — — — — — — -__ , , R^B «r<^'*g'« ?»*£»««»«)»» qfthis Mnd. How are the phenomena of the Aa< fcra Borealia recanted by theicnoraat} In what do all agree, respecting them 7 Wbera ^SQ^^S^SSSS^'^''^^'^'^^''^^^^- DeSSt£Sl*S^a«ir^ AURORA BOREAUS. 801 white light, apparently durable and immoveable, and yet so 2vanescent, that while the beholder looks upon it, it is gone At other times, they cover the whole hemisphere with iheir flickering and fantastic coruscations. On these oc* casions their motions are amazingly quick, and they aston- ish the spectator with rapid changes of form. They break out in places where none were seen before, skimming brisk- ly along the heavens ; then they are suddenly extinguished, leaving behind a uniform dusky track, which', again, is bril- liantly illuminated in the same manner, and as suddenly left a dull blank. Some nights they assume the appearance of vast columns ; exhibiting on one side tints of the deepest yellow, and on the other, melting away till they become un- dislinguishable from the surrounding sky. They have cen- erally a strong tremulous motion from end to end, which continues till the whole vanishes. Maupertitis relates, that in Lapland, '^the skv was some- limes tinged with so deep a red that the constellation Orion looked as though it were dipped in blood, and that the peo- ple fancied they saw armies engaged, fiery chariots, and a thousand prodigies." Gmelin relates, that, ^^ in Siberia, on the confines of the icy sea, the spectral forms appear like rushing armies ; and that the hissing crackling noises of those aerial fire-works so terrify the dogs and the hunters, that they fall prostrate on the ground, and will not move while the raging host is passing." Kerguelen describes " the night, between Iceland and the Ferro Islands, as brilliant as the day," — the heavens being on fire with flames of red and white light, changing to col- umns and arches, and at length confounded in a brilliant chaos of cones, pyramids, radii, sheaves, arrows, and globes of fire. But the evidence of Capt. Parry is of more value than that of the earlier travellers, as he examined the pheno- mena under the most favourable circumstances, during a period of twenty-seven consecutive months, and because his observations are uninfluenced by imagination. He speaks of th« shifting figures, the spires and pyramids, the majestic arches, and the spaTkling bands and stars which appeared within the arctic circle, as surpassing his powers of descrip- tion. They are indeed sufficient to enlist the superstitious feelings of any people not fortified by religion and philosophy. neMtribe Uieir appearance in Laplood as related by Manpertuis, and ita effect oP^'j** inhabitanta. Describe its appearance between Iceland and the Ferro Islands, as related inr Kerfuelen. Whose testimony on tliis subject is of more value than that of larmer travel' lers? Why? How does lie describe the scenes he witnessed dnno£ the polar nucnui 908 AURORA BORSAUS. The coUmra of the polar lights, are of various tints. The rays or beams are steel gray, yellowish gray, pea green, cemndine green, gold yellow, violet blue, purple, soinetimes rose red, crimson red, blood red, greenish red, orange red, and lake red. The arches are sometimes nearly black, pass- ing into violet blue, gray, gold yellow, or white bounded by an edge of yellow. The Itistre of these lights varies in kind as well as intensity. Sometimes it is pearly, some- times imperfectly vitreous, sometimes metallic. Its degree of intensity varies from a very faint radiance to a light near- ly equalling that of the Moon. Many theories have been proposed to account for this wonderful phenomenon, but there seems to be none which is entirely satisfactory. One of the first conjectures on record attributesJt to inflammable vapours ascending from the Earth into the polar atmosphere, and there ignited by electricity. Dr. Halley objects to this hypothesis, that the cause was in- adequate to produce the efiect. He was of opinion that the poles of the Earth were in some way connected with the au- rora ; that the Earth was hollow, having within it a mag- netic sphere, and that the magnetic effluvia, in passing from the north to the south, might become visible in the northern hemisphere. That the aurora borealis is, to some extent, a magnetical phenomenon, is thought, even by others^ to be pretty clearly established by the following considerations. 1. It has been observed, that when the aurora appears near the northern horizon in the form of an arch, the middle of it is not in the direction of the true north, but in that of the magnetic needle at the place of observation ; and that when the arch rises towards the zenith, it constantly crosses the heavens at right angles, not to the true magnetic meri- dian. 2. When the beams of the aurora shoot up so as to pass the zenith, which is sometimes the case, the point of their convergence is in the direction of the prolongation of the dipping needle at the place of observation. 3. It has also been observed, that during the appearance of an active and brilliant aurora, the magnetic needle of- ten beconies restless, varies sometimes several degrees, and does not resume its former position until after several hours. From these facts, it has been generally inferred that the Deacnbe the colours of the Aurora l«ht. What is one of the earliest theories a*h-aaced to explain .this phenomenon 7 How diil Dr. Halley propose to account for it? What ob- ■ervatmns have led pretty generaUy to the condiauoo. that the northern lijsfats are to WW •xteot a macDeticaJ pheiiomeoon i ^^ PARALLAX OF THE HEAVENLY BODIES. 893 auYora is in some way connected with the magnetism of thB Earth ; and that the simultaneous appearance of tne itteteor, and the disturbance of the needle, are either rela- ted as cause and effect, or as the common result of some mofe general and unknown cause. Dr. Young, in his Ifc- lures, is very certain that the phenomenon in question is in- timately connected with electro-magnetism, and. ascribes th« light of the aurora to the illuminated agency of electri- city upon the magnetical substance. It may be remarked, in support of the electro-ma^etic theory, that in majrnetisai, the agency of electricity is now clearly established; and it caa hardly be doubted that the phenomena both of electricity and magnetism are produced by one and the same cause; inasmuch as magnetism may be induced ky electricity, and tl)e electric sparic has been drawn from the tna-saet. Sir John Herschel also attributes the appearance of the aurora to the agency of electricity. This wonderful agent, says he, which we see in intense activity in lightning, ana in a feebler and more diifused form traversing the upper regions of the atmosphere in the northern lights, is present, probably, in immense abundance in every form of matter which surrounds us, but becomes sensible, only when dis- turbed by excitements of peculiar kinds. CHAPTER XXVII. PARALLAX OF THE HEAVENLY BODIES. Parallax is the difference between the altitude of any celestial object, seen from the Earth's surface, and the alti- tude of the same object, seen at the same time from the Earth's centre; or, it is the angle under which the semi- diameter of the Earth would appear, as seen from the object. The true place of a celestial body, is that point of the heavens in which it would be seen by an eye placed at the centre of the Earth. The apparent place is that point of the heavens where the body is seen from the surface of the Earth. The parallax of a heavenly body is greatest, when in the horizon ; and is called the horizontal parallax. Parallax decreases, as the body ascends toward the zenith, at which place it is nothing. The nearer a heavenly body is to the Earth, the greaier IB pamltax ? Wliat is tlie true place uf a celestial body ? What is the apparent pixee 1 Wlicre is the parallax of a heavenly body the sreateBt 7 What is this •wrBllaz eaJMl 25* 294 PARALLAX OF TH£ B£A?£NL7 BODIES. IS Its parallax ; hence the Moon has the greatest parallax cMf all the heavenly bodies, while the fixed stars, from their immense distance, have no parallax;* the semi-diameter of the Earth, at such a distance, being no more than a poinf- As the effect of parallax on a heavenly body, is to depress it below its true place, it must necessarily affect its ri^itt ascension and declination, its latitude and longitude. On this account, the parallax of the Sun and Moon must be added to their apparent altitude, in order to obtain theix trt^e altitude. The true altitude of the Sun and Moon, except when in the zenith, is al- ways affected, more or less, both by parallax aod refraction, but always in a contrary manner. Hence the mariner, in finding the latitude at sea, always cuids the parallax, and substracts the refraction, to and from the Bun's observed altitude, in order to obtain the true altitude, and thence the latitude. The principles of parallax are of great importance to as- tronomy, as they enable us to determine the distances of the heavenly bodies from the Earth, the magnitudes of the planets, and the dimessions of their orbits. The Sun's horizontal parallax being accurately known, the Earth's distance from the Sun becomes known; and the Earth's distance from the Sun being known, that of all the •planets may be known also, because we know the exact periods of their sidereal revolutions^ and according to the third law of Kepler, the squares of the times of their revolu- tions are proportional to the cubes of their mean distances. Hence, the first great desideratum in astronomy, where measure and magnitude are concerned, is the determination of the true parallax. At the late council of astronomers, assembled in Lon- don, from the most learned nations in Europe, the Sun's mean horizontal parallax was settled, as the result of their united observations, at 0° 0' 8''.5776. — Now the value of radius, expressed likewise in seconds, is 206264^.8; and this divided by 8".5776, gives 24047 for the dislante of the Sun from the Earth, in semidiameters of the latter. If we take the equatorial semidiameter of the Earth as sanction- ed by the same tribunal, at (7924-5-2=) 3962 miles, we shall have 24047X3962=95,273,869 miles for the Sun's true distance. ■ ■■ ■ ...i ■ -,-■■— - ■ ■ ■■ ■ ■—-■■■ ■ ■ - .1 ■ ■■ — ■II. — — - .— ■ - ^ •i ■ ■ ■■ ■ ■ 1 .1 ^ m * See Chapter XIV. , on the number and distance of the Stars. • How do^ the parallax of a body vary, with its altitude? How is it alfected by rfit- tance ? Give un example. What, then, are the necessary effects of parallax on the iy>- pearance ofa heavenly Ixxly? How, tlien, can we dbtain the true altitude of the 8un or Mix>n? Do paral/ax and refraction ((greet the aUitude alike! Give an example. Why are the principles of uurallax of great importanoe to astronomy J If the Sun's parol* may b« (tonv«d own tliis lo rosard to the impvrtanw ^pamilax I rROBLEMS. 295 Both the principle and the calculation of this element may be illustrated by a reference to the diagram on Plate I, of the Atlas: Thus— the parallactic angle AES = 8''.5776: is to the Earth's semidiaraeter as = 3962 miles: : as radius = 206264. "8: is to the distance ES = 95,273,869 miles, as before. Aijain : The meap horizontal parallax of the Moon is 0® 57' IT', or 3431''. In this problem, the parallactic angle AM3 isO°5r 11'' = 3431''; and 3431": is to 3962 miles:: as ^06264".8: is 238,161 miles, for the Moon's mean dis- tance from the Earth MS. — See Chapter on the Number and Distance of the Stars, j CHAPTER XI. PROBLEMS AND TABLES. PROBLEM I. TO CONVERT DEGREES, &C. INTO TIME. Rule 1. — Divide the degrees by 15, for hours ; and mul- tiply the remainder, if any, by 4, for minutes. 2. Divide the odd minutes and seconds in the samemaa- ner by 15 for minutes, seconds, &c. and multiply each re» mainder by 4, for the next lower denomination. Example 1.— Convert 32° 34' 45" into time. Thus, 32^-5- 15 = 2h. 8/ 34 ^ 15 = 2 16" 45 -- 15 == 3 Ans. 32°34'45"= 2h. 10' 19' the lime. Example 2.— If it is 12 o'clock at this place, what is the time 20° east of us ? Thus; fifteen in 20°, once, and five over; the once is 1 hour, and the 5 multiplied by 4, gives 20 minutes : the time is then 1 hour and 20 minutes past 12. Example 3.— The longitude of Haitford is 72° 5(K west of Greenwich ; what time is it at Greenwich when it is 12 o'clock at Hartford 1 Ans. 4 h. 51 min. 20 sec. Example 4. — When it is 12 o'clock at Greenwich, what is the time at Hartford ? Ans. 7h. 8m. 40 sec. A. M. NoTB.— Table VIIL is designed to facilitate calculations of this kind. Tlie itesreet being plactd in one columi^ and the corresponding time m another. W6 PROBLEMa a needs no explanation, except to observe that decrees in the left bant* enluinns may oe considered as so many minutes^ instead of degrees ; in wbicii case, the corresponding trme in the adjoining cohiain, must be read as minutea and seconds^ instead of hours and minutes. Iti like manner, the degrees in the left hanti column may be read as seconds, and the correspoad- 'ng time, as aecondv and thirds. EacAMPLB.— Find, by the table, the time corresponding to 32^ 34' W. Thus : Against 32^ is 2 h. S miu. " 34' " 2 16 sec. 11 45/-/ (( 3 Answer as above, 2h. 10m. 19 s. PROBLEM II. TO CONVERT TIME INTO DEGREES, &C. Rule. — Multiply the hours by 15, and to the product add one fourth of the minutes, seconds, &c., observing that eve- ry minute of time makes -}-°, and every second of time,-}^^ Example 1. — In 2 hours, 10 minutes, and 19 seconds, how many degrees ? Thus: 2h. 10 m. 19 s. 15 30^ Add 10 quarters, or \ of the mm. 2 SO' Add 19 quarters, or \ of the sec. 4 45^ Ans. 32« 34' 45'' This problem Is readily solved by means of Table IX. without the labour of calculation : Thus : 2 hours ^30° 10 minutes -= 2 30' 19 seconds » 4 45" Ans. 32® 34' 45" Ex. 2. — When it is 12 o'clock at Hartford, it is 4 hours 51 minutes, and 20 seconds past noon at Greenwich ; how many degrees is Hartford west of Greenwich? Thus: 15 times 4 is 60— added to i of 51, is 72° 45" and this increased by \ of 20, is 72° 50.' Ans. Ex. 3. — A Liverpool packet, after sailing several days from New York, finds the time by the Sun 2 hours and 40 minutes later than by the ship's chronometer : how far has the ship progressed on her way ? Ex. 4. — A vessel leaves Boston, and having been tossed about in foul weather for some davs, finds, that when it is 12 o'clock by the Sun, it is only ll o'clock and 50 minutes by the watch ; is the vessel east or wes^ of Boston ; and bow many degrees ? Es. 5.— The moment of greatest do»-kness during the an PK0BLEM8. 297 nular eclipse of 1831, took place at New Haven, 10 minutes after 1 o'clock. A gentleman reports that it happened pre- cisely at 1, where he observed it; and another, that it was 6 minutes after 1 where he saw it : Quere, How far east or west were these gentlemen from each other, and how many degrees from New Haven 7 ' ^ ' / ' ' . ' ' ' PROBLEiM ni. ■^ TO ^IND WHAT STARS ARE ON THE MERmiAN AT NINE o'CLOCK IN THE EVENING OP ANY GIVEN DAY. Rule. — L^ok foF-the given day of the month, at the bot- tom of the maps, and all the stars having the same degree of right ascension will be on the meridian at that time. Example 1. — What stars will be on the meridian at 9 o'clock, the 19th of January ? Solution, — On Plate III. I find that the principal stars standing over against the 19th of January, are Rigel and Capella. Ex. 2. — What stars are on the meridian the 20th of De- cember 1 Ans. Menkar and Algol. PROBLEM IV. ANY STAB BEING GIVEN, TO FIND WHEN IT CULMINATES. Rule. — Find the star's right ascension in the table, or by the map, (on the equinoctial,) and the day of the month at tie top or bottom of the map will be the day on which it culminates at 9 o'clock. Example 1. — At what time is the bright star Sirius on the meridian? Solution, — I find by the table, and by the map, that the right ascension of Sirius is 6 hours and about 38 minutes ; and the time corresponding to this, at the bottom of the map, is the 11th of February. Ex. 2. — At what time is Alpheratz, in the head of Andro- meda, on the meridian ? Ans. The 9th of November. / problem v. THE RIGHT ASCENSION ANH CECLINATION OP A PLANET BEING GI\2N, TO FIND ITS PLACE ON THE MAP. Rule. — Find the right ascension and declination of the planet on the map, and that will be its place for the given day. ^29S PROBLEMS. Example 1. — Venus's right ascension on the lat of Jau- uary, 1833, was 21 hours, 30 minutes, and her declination 16^° south; required her situation on the map? Solution, — On the right hand of the Plate II. I couni off 16f ^ from the equinoctial, on the marginal scale south, and from that pointy 30 minutes to the left, or just half the dis- tance between the XXI. and XXII. meridian of right as- cension, and find that Venus, that day, is within two degrees of Delta Capricorni, near the constellation Aquarius, in the zodiac. Note. — It is to be remembered, that the planets will always be found within the Ihnits of the zodiac, as represented in tl^ maps. By means of Table VII. the pupil can find at any time th« situations of all the visible f)Ianets, on the maps; and this will enable him to determine their positioti n the heavens, without a chance of niiatake. By this means, too, he can draw for himself the path of the planets from month to month, and trace ttieir course among the stars. This is a pleasant and useful exercise, and is practised extensively in some academies. The pupil draws the map ia the first place, or such a portion of it as to include the zodiacal constella- tions ; tlien, havinsr dotted the position of the planets from day to day, as indicated in Table~VII., tlieir path is easily traced with a pea or pencil. Ex. 2. — Mars' right ascension on the With of March, 1833. is 5 hours, 1 minute, and his declination 24f^ north; requir- ed his situation on the map ? Solution, — I find the fifth hour line or meridian of right ascension on Plate III. and counting upwards from the equi- noctial 24?^^, I find that Mars is between the horns of Taurus, and about 5° S. W. of Beta Aurigae. Ex. 3. — Required the position of Jupiter and Saturn on the 13th of February and the 25th of May ? When the right ascension and declination of the planets are not given,, they are to be sought in Table VII. PROBLEM VI. rO FIND AT WHAT MOMENT ANY STAR WILL PASS TUB MERIDIAN ON A GIVEN DAY. Rule. — Substract the right ascension of the Sun from the star's right ascension, found in the tables; observing to add 24 hours to the star's right ascension, if less than the Sun's, and the diflfeience will show how may hours the star culmi> nates after the Sun. Example 1. — At what time will Procyon pass the meridi- an the 24th of Februai v ? Solution,--^, A. of Procyon 7h. 30m. 33s.+24h. 31 30' 33" R. A. of Sun, 24th of Feb. 22 29 1 Ans., _ 9 O 32 That is, Vcn, 32s. past 9 o'clock in the evening. PS0BLEBI8. 209 Ex. 2, — ^At what time will Denebola pass the meridian on •be first of April? Solntion.-^R. A. of Denebola is llh. 40' 32'' R. A, of Sun, April 1, 41 25 Ans. 10 59 7 That is, at 59 minutes, 7 seconds, past 10 in the evening. Ex. 3. — At what time on the first day of each month, from January to July, will Alcyone, or the Pleiades, pass the me- ridian ? Ex. 4. — At what time will the Dog Star, or Sirius, culmi- nate on the first day of January, February, and Maich ? Ex. 5. — How much earlier will Spica Vir^inis pass the meridian on the 4lh of July, than, on the 15th of May ? — Ans. 3 hours, 25 minutes. probij:m VII. TO FINn WHAT STAR3 WILX. BE ON OR NEAREST THE MERmiAN AT ANY GIVEN TIME. RcLE. — Add the given hour to the Sun's right ascension, found in Table III., and the sum will be the right ascension of the meridian, or mid-heaven ; and then find in Table II. what star's right ascension corresponds with, or comes near- est to it, and. that will be the star required. ExAa'irLE ]. — What star will be nearest the meridian at 9 o'clock in the evening of the 1st of September? Solution. — Sun's right ascension 1st September, lOh 40' 30" Add the time from noon 9 Right ascension of the meridian 19h 40' 30" Nov/ all the stars in the heavens which have this right as- cension, will be on the meridian at that time: On looking into Table II. the right ascension of Altair, in the Eagle, wiJl be fonnd to be 19h. 40m. ; consequently Altair is on the meridian at the time proposed ; and Delta, in the Swan, is less than two minutes past the meridian. Ex. 2. — Walking out m a bright evening on the 4th of Sep tember, I saw a very brilliant star almost directly over head ; I looked on my watch, and it wanted 20 minutes of 8 ; required the name of the star ? Solution, — Sun's d«oIuMUio& 4th of September, lOh 5r 22" Add the time from noon 7 40 Oives R. A. of Ljrra^ nefftrly 18 31 22 SOO / PR0)ILEMS. Ex. 3. — About 8f minutes after 8 in the evening of the 11th of February, I observed a bright star on the meridian, a little north of the equinoctial, and 1 minute before 9 a still brighter one, further south ; required the names of the stars ? PROBLEM VIII. TO FIND WHAT STARS WILL CULMINATE AT 9 o'CLOCK IN THE EVENING OF ANY DAY IN THE YEAR. Rule. — Against the day of the month in Table IV., find the right ascension of the mid-heaven, and all those stars in Table II. which have the same, or nearly the same right as- cension, will culminate at 9 P. M. of the given day« Example 1. — What star will culminate at 9 in the even- ing of the 26th of March ? Solution. — I find the right ascension of the meridian, at 9 o'clock in the evening of the 26lh of March, is 9h 19' 37": and on looking into Table II., I find the right ascension of Alphard, in the heart of Hydra, is 9h 19' 23''. The star is Alphard. Ex. 2. — What star will culminate at 9 in the evening of the 28th of June ? Ans. Aphacca. I'RODLEM IX. TO FIND THE SUN's LONGITUDE OR PLACE IN THE ECLIPTic, ON ANY GIVEN DAY. Rule. — On the lower scale, at the bottom of the HPlan" isphere, (Plate VIII.) look for the given day of the month, then the sign and degree corresponding to it on the scale immediately above it, will show the Sun's place in the ecliptic- Example 1. — Required the Sun's longitude, or place ia the ecliptic, the 16th of September. Sohtiion. — Over the given day of the month, September 16th, stands 5 signs and 23 degrees, nearly, which is the Sun's place in the ecliptic at noon on that day ^ that is, the Sun is about 23 degrees in the sign Virgo. N. II. If tlie 5 si^s be multiplied by 30^ and the 23 dogrces be added to % it will give the longitude in degrees, 173. Ex. 2. — Required the Sun's place in the ecliptic at nooa, on the 10th of March. ^ . . ' ^ PfiOBLEMS. 901 PROBLEM X. GTVEN TH£ SUN's LONGITUDE, OR PLACE IN THE ECLIPTIC, TO FIND HIS RIGHT ASCENSION AND DECLINATION. Rule. — Find the Sun's place in the ecliptic, (the curbed line which runs through the hody^ of the planisphere,) and with a pair of compasses ta^ke the nearest distance between it and the nearest meridian, or hour circle, which being ap- plied to the graduated scales at the top or bottom of the planisphere, (measuring from the same hour circle,) will show the Sun's risht ascension. Then take the shortest distance between the Sun's place in the ecliptic and the nearest part of the equinoctial, and apply it to either the east or west marginal scales, and it will give the Sun's de- cUnation. Example 1. — The Sun's longitude, September 16th, 1833, is 5 signs, 23 degrees, nearly ; required his right ascension, and declination. Solution. — The distance between the Sun's place in the ecliptic and the nearest hour circle-being taken in the com- passes, and applied to either the top or bottom graduated scales, shows tbe right ascension to be about 11 hours 35 minutes ; and the distance between the Sun's place in tbe ecliptic, and the nearest part of the equinoctial, being applied to either the east or west marginal scales, shows the decli- nation to be about 2*^ 45', which is to be called north, because the Sun is to the northward of the equinoctial : hence the Sun's right ascension, on the given day, at noon, is about II hours 35 minutes, and his declination 2^ 45' N. Ex. 2. — The Sun's longitude March 10th, 1833, is 11 signs, 19 degrees, nearly ; required his right ascension and declination ? Ans. R. A. 23 h. 21 niin. Decl. 4° 11' nearly. I PROBLEM XL TO FIND THE RIGHT ASCENSION OF THE MERIDIAN AT ANT GIVEN TIME. KuLE.—Find the Sun's place in the ecliptic by Problem IX. aikd his right ascension by Problem X., to the eastward of which, count off the given tinae from doo\i, and it will show the right ascension of the meridian, or mid- heaven. Example 1. — Required the right ascension of the meridi- an 9 hours 25 minutes past noon, September 16th, 1833. Solution^-^By ProbleoM IX. and X.^ th« Sun's right ascen- 20 303 pftOBUBMa sion at noon of the given day, is 11 hours 35 minutes ; to the eastward of which, 9 hours and 25 minutes ^the given time) being counted off, shows the right ascension of the meridian to be about 21 hours. Ex. 2. — Required the right ascension of the meridian at ferred from the left, and completed on the right, as if the two outside edges of tjie planisphere were joined together. f PROBLEM x4l. 70 FIND WHAT STABS WILL BE ON OR NEAR THE MERIDIAN AT ANY GIVEN TIME. Rule. — Find the riffht ascension of the meridian by Problem XI. over which lay a ruler, and draw a pencil line along its edge from the top to the bottom of the planisphere, and it will show all the stars that are on or near the meridian. Example 1. — Required what stars will be on or near the meridian at 9 hours 25'rainutes past noon, Sept. 16th, 1833 ? Solution. — The right ascension of the meridian by Prob- lem XI. is 21 hours : this hour circle, or the line which passes up and down through the planisphere, shows that no star will be directly on the meridian at the given time ; but that Alderamin will be a little to the east, and Deneb Cygni, a little to the west of it; also Zeta Cygni, and Gamma and Alpha in the Little Horse, very near it on the east. PROBLEM xin. TO FIND THE EARTH's MEAN DISTANCE FROM THE SUN. Role. — As the Sun's horizontal parallax is to radius, S6 is the semi-diameter of the Earth to its distance from tht Sun. By Logarithms, — As tangent of the Sun's horizontal par- allax is to radius, so is the Earth's semi-diameter to hei mean distance from the Sun. &".8776 : ^06lM'^8 : : 39G2 : 9^,273,809 oittet / / / - rROBLSBIS. 303 By Logarithrru. A3 tangent of Sun's horizontal parallax, 8".Ci776 — 5.6189407 lu to radius, or 90®, ~ lO.lXXMOOO So is the Earth's semi-diameter, 39G2. — 3.5979145 To the Earth's distance, ^273,809 - 7.9789738 PROBLEM XIV. rO FIND THE DISTANCE OF ANY PLANET FROM THE SUN, THAT OF THE EARTH BEING KNOWN. Rule. — Divide the square of the planet's sidereal rerolu- tion round the Sun, by the square of the Earth's sidereal re- volution, and multiply the cube root of the quotient by the Earth's mean distance from the Sun. By Logarithms, — From twice the logarithm of the plan- et's sidereal revolution, substract twice the logarithm of the Earth's sidereal revolution, and to one third of the remain- der, add the logarithm of the Earth's mean distance from the Sun. ExAMn.B.— Required Mercury's mean distance from the SoO) that of the Earth bein/ar 95,273,869 miles. Mercury's sidereal revolution is 87.969258 days, or 7600543^^8912 : The Earth's sidereal revolution is 365.256374417 days, or 31558151".5 7600543 .» 31568R1".5 7600543.9 995916962096952.25 by which divide 57768267575827.21 and the quotient will be .052005106713292, the cube root of which in 0.3870977, and tbid multiplied by 94,881,891, gives 36,727,607 miles, for Mercury's distance from the Sun. This problem may be performed by logarithms is as many tninutee&s the former method requires hours. Mercury's SitL Rev. 7600543".9 log. « 6.8808417X2 13.7616894 Earth's Sid. Rev. 31558151". Jog. - 7.4991302X2 14.9982604 i>-2.763129» 1.5878097 Add. log; of the Earth's mean distance, 7.9789733 Mercury's distance, 36,88W22. Ans. 7.5667835 If the pupil have not already learned the use of logarithms, this problem will satisfy him of their unspeakable advantage over all other modes of com- putation. By reviewing the above calculation, he will perceive that instead of multiplying 31558151' .5 by itself, he need only rauUiply its logarithms by ttool and, instead of extracting the cube root oi 0.058005100713292, he need only divide its logarithm by three ! and, instead of multiplying 0.3870977, by 95,273, 869, he need only add their logarithms together. lie need not think himself a dull scholar, if by the former method he come to the true result in fivt hours ; nor remarkably quick, if by the latter he come to it in^rc ndnuiea. PROBLEM XV. TO FIND THE HOURLY MOTION OP A PLANET IN ITS ORBIT. Rule. — Multiply the planet's mean distance from the Sun by 6,2831853, and divide the product by the time of the planet's sidereal revolution, expressed in hours, and the decimals of an hour. 304 PHOBLBMa By Logarithms, — Add 0,7981799 to the logarithm of che planet's mean distance ^rom the Sun, and from the sum substract the logarithm of the planet's revolution expressed in hours. £xAiiPLB.— Required the Earth's honrly motion in its orbit Los. of Earth's distance — 7.9789738-H).7961799 — 6.7771537 Substract log. of Earth's revolatioo ^9428090 Gives Earth's horary motion, C6,288 miles, — 4.8343M7 PROBLEM XVL K ^ ^J TO FIND THE HOURLY MOTION OF A PLANET ON ITS AXIS. Rule. — Multiply the diameter of the given planet by 3.14159, and divide the product hy the period of its diurnal rotation. By JLofartYAm«.— Add 4.0534524 to the logarithm of the planet's diameter, and from the sum substract the logarithm of its diurnal rotation, expressed in seconds. Earth's diameter, 7921 log. ^ d.89fl044S Add log. of aGOCH-loK- of 3.14159 - 4.0E334521 7.9503969 Babstractlof. diurnal rotation, 28 h. 66' 4".09 * 4!9953263 Ans. I(y04)9 miles - 3.0170706 PROBLEM XVn. TO FIND THE RELATIVE MAGNITUDE OF THE PLANETa Rule. — Divide the cube of the diameter of the lai^r planet, by the cube of the diameter of the less. By Logarithms. — From three times the logarithm of the larger, substract three times the logarithm of the less. ExAicpLB.— How much does \he size of the Earth exceed that of the Moon? Earth's diameter, 7912 log. 3.8982963X3 - 1 1.6948589 Moon's diameter, 2160 log. 3.3343376X3 - 10.0090128 Tlie Earth exceeds the Moon, 49.1865 times. Ans. 1.6918161 In this example, 7912 miles is assumed as the mean between the Earth's equatorial and polar diameter: the former being 79dl, and the latter 7898 miles. PROBLEM XVm. TO FIND THE PROPORTION OF SOLAR UOHT AND HEAT AT BACH OF THE PLANETS. Rule. — Divide the square of the planet's greater distance from the Sun, by the square of the less. — Or, substract twice the logarithm of the greater distance, from twice the loga- rithm of the less. PROBLEMS. 305 Example. — How much greater is the Sun^s light and neat at Mercury, than at the Earth 7 l^g. of Earth's distance 7.9789738X2 - 15.9599476 — of Mercury's 7.6667959X2 - 15 1335918 Ana. 6.6736 tiuics greater - 0.82435G8 PROBLEM XIX. TO FIND THE CIRCUMFERENCE OP THE PLANETS. Rule. — Multiply the diameter of the planet by 3.14159; or, add the logarithm of the planet's diameter to 0.4971499. PROBLEM XX. TO FIND THE CIRCUMFERENCE OP THE PLANETARY ORBITS. Rule. — Multiply the planet's mean distance from the Sun, by 6.2831853 : or, to the logarithm of the planet's mean distance, add 0.7981799, and the sum will be the lo- garithm of the answer. PROBLEM XXL TO FIND IN WHAT TIME ANY OP THE PLANETS WOULD PALL TO THE SUN IF LEFT TO THE FORCE OP GRAVITATION ALONE. Rule. — Multiply the time of the planet's sidereal revolu- tion, by 0.176776; the result will be the answer. By Logarithms. — From the logarithm of the planet's si- dereal revolution, substract 0.7525750, and the remainder will be the logarithm of the answer, in the same denomina- tion as the sidereal revolution. Required the times, resipectively, in wbicit the several planets would falk to the Sun by the force of gravity. Planets would fall to Days. B M. S. Logaiithms. the Sun. Mercury, 15 13 13 IG 6.1282686 Venus, 39 17 19 22 6.5355424 Earth, 64 13 38 55 6.7465357 Mars, 121 10 36 3 7.a208Sl7 Jupitor, 765 21 33 35 7.82015849 Saturn. 1901 • 23 21 4 8.2157186 llerschcl, 54iM 16 52 1 8.6708897 Mooa u> the Earth, 4 19 54 57 6.6204459 26* 5S8SSS£SSiB8 spMIMi .5iiJ5iS=S:,a.i_g_% na, SL „:isssssssissg l.iMiMiii r 'I ill 8 J'i? 'j F- lisk,J,l,ii__c il iiiiiiiii E ' Containing the names of Ibe CoiutellanonB, iho minber ■nd magrunidi of ihe Sura in each, and the daye on which thef come lo the merid- ian at 9 o'clock in the evening. TABLE I.— Ccmtiaaed. TABLE 11. Sxbibitiii» the Right Ascension and Declination of the prmcips} Fixed Stars, and the time of their coming to the Meridian. These to which S is aimezed cure in SoiUh declination ; tlie otbei-s are in North declination. ^ Names of the Stars. 3 Right Ascension. Declination. On the Merid. 1 • Persei, H. 3 47 8 o 39 31 37 Jan. 1 2 y Eridanf, 3 3 50 15 13 59' 4S. 2 3 Eridani, 3 4 3 31 7 16 32S. 5 4 fl Tanri, 3 4 18 52 18 8 18 8 5 A Tattri, Aldebaran, 1 4 26 21 16 10*^1 4 10 6 7 yS Eridani, 3 4 39 35 5 18 i OS. 13 at Aurigaj, Capella, 1 5 4 22 45 49 10 19 8 /d Orionis^ Rigel, 1 5 6 31 8 23 55S. 20 9 Tanri, El Nath, 2 5 15 44 28 27 39 22 10 ti Orionis, 3 5 15 36 2 33 17S. 22 11 > Orionis, Bellatriz, 2 5 16 11 6 11 32 22 12 /8 LepcriSj Nibal, 3 5 21 22 20 53 46S. 23 13 ^ Orionis, Mintaka, 2 5 23 29' 25 39S. 24 14 « Leporis, Arneb, 3 5 25 33 17 56 50S. 24 15 • Orionis, Anilam, 2 5 27 44 1 18 49S. 25 16 f Tauri, 3 5 27 53 21 2 7 25 17 f Orionis, Alnitak, 2 5 32 20 2 2 9S. 26 18 A ColumbsB, Phaet, 2 5 33 9 34 10 2S. 26 19 V Orionis, Saiph, Colnmbae, 3 5 39 29 9 44 2S. 27 20 3 5 45 6 35 50 12S. 29 21 a, Orionis, Betel guese 1 5 46 8 7 22 6 29 22 y8/8AnrigaB,Menkalina 2 5 47 17 44 55 24. 29 3 Geminornm, Tejat, Ji 6 4 54 . w 23 1 Feb. 1 24 A* \Triiiinomm, 3 6 12 54 22 35 48 4 25 3 126'^ 127.* 128 f 129f 131? 132 « 133; 134* 135 V 136/^ 137^ 138^ 140* 141/3 142 >^ /* Ophia.,Yed,orJed^ Ophiuchi, Hercules, Scorpii, Antares, DracoDis, HerculeSjRatilicus, Ophiuchi, Triang. AustraliS| Herculis, Scorpii, 1 Scorpii, Scorpii, HerculiSj Ophiuchi, Her., Ras Algethi, Herculis, Draconis, Arae, Scorpii, Lesath, Scorpii, Ophiu., Ras Alhag, Ophiuchi, Cheleb, Ophiuchi, 143 > 144; > 145'«r 146'f 147!* 148> 149;/3 150> 15l!fl 152 cT 153;^ 154i>' 155 • 156^ 157 «r 158* 159/ Draconis. Rastaben, 2 Sagiltairii, Sagittarii, Sagittarii, Lyroe, Vega, Ursae Minoris, Lyrae, Sagittarii, Serpentis, Alga, Lyree, Sagittarii, Lyrae, Jugom., Aquilae, A., Deneb el OksU), Sagittarii, Sagittarii, Draconis, be t Right Asceosion. I o 3 3 1 3 3 3 2.3 3 3 3 3 3 2.3 2.3 3 3 3 2.3 3 2 3 3 H. 16 16 16 1(1 16 16 16 16 16 16 16 16 16 17 17 17 17 17 17 17 17 17 17 2.3 17 3 17 3 2.3 1 3 2.3 2 3 3 3 3 3 3 3 3.4 3 18 18 18 18 18 18 18 18 18 18 18 18 18 19 19 M. 8. 5 36 9 39 14 23 19 10 21 12 23 22 27 45 31 3 34 59 39 4 40 8 42 52 54 14 50 7 2 8 20 8 23 18 57 22 58 25 20 28 11 35 30 39 56 52 55 10 12 26 28 43 44 47 49 52 52 44 ■» d 1 48 11 6 55 58 36 6 1 11 52 26 57 44 Declination. 3 4 19 26 61 21 10 68 31 33 37 41 31 15 14 25 65 49 36 42 12 4 2 59 12 54 19 19 29 51 30 29 34 38 86 33 26 3 36 30 32 14 13 21 40 67 // 15 18S. 16 37S. 33 1 3 7& 53 38 57 36 13 15S. 42 23S. 54 39 58 40S. 45 14S. 3 33S. 10 40 30 35S. 35 17 2 43 55 12 43 54s, 58 24S. 52* 55S. 41 20 38 40 46 42 On the' & MerM. ^ 30 42 24 40S. 53 28S. 27 US. 38 35 47 10 33 29 42S. 59 20 41 28 6 40S. 27 47 50 4 , 37 20 16 56S. 55 9S. 21 59 July. 7 8 9 11 11 12 13 14 15 16 1 16 17 19 21 23 23 23 24 27 27 28 30 31 Aug. 3 4 8 8 12 12 17 17 18 18 19 19 19 20 21 24 24 TABLS Il.-'^ontinutd. Kames of the Stars. • Righi \ Declination. Ascensi Cephei, Er Rai, 199* Andromedae, Alph., 200 P CassiopeJae, Chaph, 201 > Pegasi, Algenib, 202^ Hydrus, 203 * Pha?nicis, 204^ Andromedae, 205 * Cassiop., Schedir, 206 fi Ceti, Deneb Kaitos, 207 > Cassiopeia, 208 * U. M. Alruccabah, 209/8 Andro.,Mirach, i >> A™nilL . Declination. 'On ihe! «" Ascension. ; Merid. « H. 3 23 223 324 3! 210 if 211* 21-2 £ 213^ 214/8 215 a 210 y 217* 2l8o 219 2-29/ 230/ 231 232 Cassio., Ruchbah, Eradani, Achernar, Cassiopeiae, Ceii, Eaton Kaitos, Arietl?, Piscium, El Rischa, Andro., Almaach, Arietis, or El Nath, Ceti, Mira, Ceti, Ceti, Ceti, Persei, Ceti, Menkar, Persei, Algol, Fornax Chemica, Eridani, Persei, Algeneb, Endani; Persei, Eridani, Pleiades, Alcyone, ^ Persei, 3 2.3 3 3 2 3 2.3 2 1 1 32 16 59 46 36 4 39 15 56 18 1 30 36 31 5 35 12 46 41 19 45 // 76 41 28 10 58 13 14 15 ',78 12 43 12 29 56 55 37 il8 54 59 48 :88 25 >34 44 52 9 47 22 7S. 12S. 13 17S. 41 7 10 3 1 3 3 3 3 2 2 2 3 3 3 3 2 ▼ar 3 3 2 3 3 3 3 1 1 1 1 1 1 1 1 2 2 2 14 31 42 43 45 53 53 57 10 30 31 2 34 2 52 2 2 3 3 3 3 3 3 3 53 56 5 7 12 25 31 S5 37 57 21 11 35 45 38 54 47 36 38 31 38 13 33 52 20 31 26 32 4 31 34 59 58 62 11 20 1 41 22 3 12 2 52 3 40 29 9 49 10 47 10 3 44 21 54 12 37S. 50 42 9 36S. 59 30 57 19 31 32 40 11 43 59Sv 23 15S. 34 49S. 31 57 50 46 25 54 18 30 39 50S. 26 31S. 15 38 1 26S. 14 54 20 16S. 35 4 Nov. Dec. 10 10 11 14 14 17 17 18 21 24 24 28 1 4 4 5 7 8 11 15 15 16 20 20 21 23 23 25 27 29 30 33 31 23 26 Jan. I 1 TABLE III. Kxhibltin^ the Sun's Right Ascension, in Time, for every day in the year. i January. February. March. April. May. June. h. m. s. h. ra. s. h. m. s. h. m. s. h. in. s. h. m. 8. 1 18 46 21 20 58 43 22 47 51 41 25 2 32 36 4 35 .4 1 2 18 50 46 21 2 47 22 51 36 45 3 2 36 25 4 39 19 2 3 18 55 11 21 6 50 22 55 19 48 42 3 40 14 4 43 25 3 4 18 59 35 21 10 53 22 59 3 52 20 2 44 4 4 47 31 4 5 19 3 59 21 14 54 23 2 46 55 59 2 47 55 4 51 38 5 6 19 8 22 21 18 55 23 6 28 59 57 2 51 46 4 55 45 6 7 19 12 45 21 22 55 23 10 10 1 3 16 2 55 37 4 59 52 7 8 19 17 7 21 26 54 23 13 52 1 6 56 2 59 30 5 3 59 8 9 19 21 29 21 30 53 23 17 33 1 10 35 3 3 22 5 8 7 9 10 19 25 50 21 34 ^0 23 21 14 1 14 15 3 7 16 5 12 15 10 11 19 30 11 21 38 4723 24 54 1 17 55 3 11 10 5 16 24 11 12 19 34 3i 21 42 43 23 28 35 1 21 35 3 15 4 5 20 32 12 13 19 38 50 21 46 38 23 32 14 1 25 15 3 19 5 24 41 13 14 19 43 9 21 ,50 33 23 35 54 1 28 56 3 22 55 5 28 50 14 K) 19 47 27 21 54 27 23 39 34 1 32 38 3 26 52 5 32 59 15 16 19 51 45 21 58 20 23 43 13 1 36 19 3 30 49 5 37 9 16 17 19 56 1 22 2 12 23 46 52 1 40 1 3 34 46 5 41 18 17 18 20 18 22 6 4 23 50 31 1 43 44 3 38 44 5 45 28 18 19 20 4 33 22 9 55 23 54 9 1 47 26 3 42 43 5 49 37 19 20 20 8 48 22 13 45 23 57 48 1 51 10 3 46 42 5 53 47 20 21 20.13 2 22 17 35, 1 26 1 54 53 3 50 42 5 57 57 21 22 20 17 15 22 21 24 5 4 1 58 37 3 54 42 6 2 7 22 23 20 21 27,22 25 13, 8 43 2 2 22 3 58 44 6 6 16 23 24 20 25 39,22 29 1 12 21 2 6 7 4 2 45 6 10 26 24 25 20 29 50.22 32 48, 15 59 2 9 53 4 6 47 6 14 35 25 26 20 34 0,22 36 35 19 37 2 13 39 4 10 49 6 18 44 26 27 20 38 9 22 40 21 23 15 2 17 25 4 14 52 6 22 54 27 26 20 42 18i22 44 6 26 53 2 21 12 4 18 56 6 27 3 28 29 20 46 25 30 31 2 24 59 4 23 6 31 11 29 30 20 50 32 34 9 2 28 47 4 27 4 6 35 20 30 31 20 54 38 37 47 4 31 8 31 TABLE III.—CoDtinuecL 1 July. August Bept Oct Nov. Dec. • & h. m. 8. h m. 8. h. m. 8. h. m. 8. h. m. 8. h. m. 8. 1 6 39 28 844 22 10 40 30 12 28 35 14 24 45 16 28 29 I 3 6 43 36 8 48 15 10 44 8 12 32 12 14 28 41 16 32 48 2 3 6 47 44 8 52 7 10 47 45 12 35 50 14 32 37 16 37 8 3 4 6 51 52 8 55 59 10 51 22 12 39 28 14 36 34 16 41 29 4 5 6 55 59 8 59 50 10 54 59 12 43 6 14 40 32 16 45 50 5 6 7 6 9 3 40 10 58 36 12 46 45 14 44 30 16 50 12 6 7 7 4 12 9 7 30 11 2 12 12 50 24 14 48 30 16 54 34 7 8 7 8 18 9 11 19 11 5 48 12 54 4 14 52 30 16 58 57 8 9 7 12 24 9 15 8 11 9 24 12 57 44 14 56 31 17 3 20 9 10 7 16 30 9 18 56 U 13 13 1 24 15 34 17 7 44 10 11 7 20 35 9 22 44 11 16 36 13 5 5 15 4 37 17 12 9 11 12 7 24 39 9 26 31 11 20 12 13 8 47 15 8 41 17 16 33 12 13 7 28 43 9 30 18 11 23 48 13 12 29 15 12 45 17 20 58 13 14 7 32 47 9 34 4 11 27 23 13 16 12 15 16 51 17 25 24 14 15 7 36 50 9 37 49 11 30 59 13 19 55 15 20 57 17 29 49 15 16 7 40 53 9 41 34 11 34 34 13 23 38 15 25 5 17 34 15 16 17 7 44 55 A 45 19 9 49 3 11 38 10 13 27 23 15 29 13 17 38 41 17 18 7 48 57 11 41 45 13 31 8 15 33 22 17 43 8 18 19 7 52 58 9 52 46 11 45 21 13 34 53 15 37 32 17 47 34 19 20 7 56 59 9 56 29 11 48 56 13 38 39 15 41 42 17 52 1 20 21 8 59 10 12 11 52 32 13 42 26 15 45 54 17 56 27 21 22 8 4 59 10 3 54 11 56 8 13 46 13 15 50 6 18 54 23 23 8 8 58 10 7 35 11 59 43 13 50 1 15 54 19 18 5 21 23 24 8 12 56 10 11 16 12 3 19 13 53 50 15 58 33 18 9 47 24 35 8 16 54 10 14 57 12 6 55 13 57 39 16 2 47 18 14 14 25 26 8 20 52 10 18 37 12 10 31 14 1 29 16 7 2 18 18 40 26 27 824 48 10 22 17 12 14 7 14 5 20 16 n 18 18 23 7 27 28 828 44 10 25 56 12 17 44 l4 9 12 16 15 35 18 27 33 28 29 8 32 39 10 29 35 12 21 21 14 13 4 16 19 52 18 31 59 29 30 8 36 34 10 33 14 12 24 57 14 16 57 16 24 10 18 36 24 30 31 840 38 10 36 52 14^51 m 18 40 60 31 TABLE IV. Showing the Right Ascension of the Mid-Heaven at 9 o'clock Li the evening, for every day in the year. • January. February. March. April. May. June. h. in. 8. h. m. s. h. in. s. h. m. 8. h. in. 8. h m. 8. 1 3 46 21 5 58 4^ 7 47 51 9 41 25 11 32 36 13 35 14 1 2 3 50 46 6 2 *7 7 51 35 9 45 3 11 36 25 13 39 19 2 3 3 55 11 6 6 50 7 55 19 9 48 42 11 40 14 13 43 25 3 4 3 59 35 6 10 53 7 59 3 9 52 20 11 44 4 13 47 31 4 5 4 3 59 6 14 54 8 2 46 9 55 59 11 47 55 13 51 38 5 6 4 8 22 6 18 55 8 6 28 9 59 57 11 51 46 13 55 45 6 7 4 12 45 6 22 55 8 10 10 10 3 16 11 55 37 13 59 52 7 8 4 17 7 6 26 54 8 13 52 10 6 56 11 59 30 14 3 59 8 9 4 21 29 6 30 53 8 17 33 10 10 35 12 3 22 14 8 7 9 10 4 25 50 6 34 50 8 21 14 10 14 15 12 7 16 14 12 15 10 11 4 30 11 6 38 47 8 24 54 10 17 55 12 11 10 14 16 24 11 12 4 34 31 6 42 43 8 28 35 10 21 35 12 15 4 14 20 32 12 13 4 38 50 6 46 38 8 32 14 10 25 15 12 19 14 24 41 13 14 4 43 9 6 50 33 8 35 54 10 28 56 12 22 55 14 28 50 14 15 4 47 27 6 54 27 8 39 34 10 32 38 12 26 52 14 32 59 15 16 4 51 45 6 58 20 8 43 13 10 36 19 12 30 49 14 37 9 16 17 4 56 1 7 2 12 8 46 52 10 40 1 12 34 46 14 41 18 17 18 5 18 7 6 4 8 50 31 10 43 44 12 38 44 14 45 28 18 19 5 4 33 7 9 55 8 54 9 10 47 26 12 42 43 14 49 37 19 20 5 8 48 7 13 45 8 57 48 10 51 10 12 46 42 14 53 47 20 21 5 13 2 7 17 35 9 1 26 10 54 53 12 50 42 14 57 57 21 22 5 17 15 7 21 24 9 5 4 10 58 37 12 54 42 15 2 7 22 23 5 21 27 7 25 13 9 8 43 11 2 22 12 58 44 15 6 16 23 24 5 25 39 7 29 1 9 12 21 11 6 7 13 2 45 15 10 26 24 25 5 29 50 7 32 48 9 15 59 11 9 53 13 6 47 15 14 35 25 *26 5 34 7 36 35 9 19 37 11 13 39 13 10 49 15 18 44 26 27 5 38 9 7 40 21 9 23 15 11 17 25 13 14 52 15 22 54 27 28 5 42 18 744 6 9 26 53 11 21 12 13 18 56 15 27 3 28 20 5 46 25 9 30 31 11 24 59 13 23 15 31 11 29 30 5 50 32 9 34 9 11 28 47 13 27 4 15 35 20 30 21 5 54 38 9 37 47 13 31 8 31 27» TABLE IV^^-Contiimed. • July. August Sept Oct Nov. Dec. 1 h. m. 8. h. m. B. h. m. 8. h. m. s. h. m. B. h. m. B. 1 15 39 28 17 44 22 19 40 30 21 28 35 23 24 45 1 28 29 1 2 15 43 36 17 48 15 19 44 8 21 32 12 23 28 41 1 32 48 3 3 15 47 44 17 52 7 19 47 45 21 35 50 23 32 37 1 37 8 3 4 15 51 52 17 55 59 19 51 22 21 39 28 23 36 34 1 41 29 4 5 15 55 59 17 59 50 19 54 59 21 43 6 23 40 32 1 45 50 5 6 16 6 18 3 40 19 58 36 21 46 45 23 44 30 1 50 12 6 7 16 4 12 18 7 30 20 2 12 21 50 24 23 48 30 1 54 34 7 8 16 8 18ll8 11 19 20 548 21 54 4 23 52 30 1 58 57 8 9 16 12 24118 15 8|20 9 24 21 57 44 23 56 31 2 3 20 9 10 16 16 30il8 18 56120 13 22 1 24 34 2 744 10 11 16 20 35,18 22 44 20 16 36 22 5 5 4 37 2 12 9 11 12 16 ^ 39 18 26 31 20 20 12 22 8 47 8 41 2 16 33 12 13 16 28 43 18 30 18 20 23 48 22 12 29 12 45 2 20 58 13 14 16 32 47;i8 34 4 20 27 23 22 16 12 16 51 2 25 24 14 15 16 36 50 18 37 49 20 30 59 22 19 55 20 57 2 29 49 15 16 16 40 53|l8 41 34 20-54 34 22 23 38 25 5 2 34 15 16 17 16 44 55 18 45 19 20 38 10 22 27 23 29 13 2 38 41 17 18 16 48 57:18 49 3 20 41 45 22 31 8 33 22 243 8 18 19 16 52 58 18 52 46 20 45 21 22 34 53 37 32 2 47 34 19 20 16 56 59 19 56 29 20 48 56 22 38 39 41 42 2 52 1 30 21 17 59 19 12 20 52 32 22 42 26 45 54 2 56 27 21 22 17 4 59 19 3 5420 56 8 22 46 13 50 6 3 54 22 23 17 8 58 19 7 35 20 59 43 22 50 1 54 19 3 5 21 23 24 17 12 56 19 11 16121 3 19 22 53 50 58 33 3 9 47 24 25 17 16 54 19 14 57 21 6 55] 22 57 39 1 2 47 3 14 14 25 26 17 20 52 19 18 37 21 10 31 23 1 29 17 2 3 18 40 26 27 17 24 48 19 22 17 21 14 7 23 5 20 1 n 18 3 23 7 27 28 17 28 44 19 25 56 21 17 44 23 9 12 1 15 35 3 27 33 28 29 17 32 39 19 29 35 21 21 21 23 13 4 1 19 52 3 31 59 29 30 17 36 34 19 33 14 21 24 57 23 16 57 1 24 10| 3 36 24 30. 31 17 40 28 19 36 53 23 20 51 1 340 50 31 TABLE V. ► Exhibiting the Sun's Declination for every day in the 3rear. 1 January. Febniary. o 1 II March. April. May. June. _l o / ff o / // o / II o / // o t It 1 23 1 52 17 8 57 7 39 11 4 27 37 15 22 22 1 44 1 2 22 56 45 16 51 46 7 16 22 4 50 43 15 18 26 22 9 49 2 3 22 51 10 16 34 18 6 53 27 5 13 44 15 36 16 22 17 30 3 4 22 45 8 16 16 32 6 30 26 5 36 39 15 53 50 22 24 4S 4 5 22 38 39,15 58 29 6 7 20 5 59 28 16 11 8 22 31 43 6 6 22 31 43,15 40 11 5 44 9 6 22 11 16 28 10 22 38 14 6 7 22 21 20 15 21 36 5 20 53 6 44 48 16 44 56 22 44 21 ■7 8 22 16 31 15 2 46 4 57 34 7 7 17 17 1 25 22 50 4 8 9 22 8 16 14 43 40 4 34 lit 7 29 40 17 17 37 22 56 23 9 10 21 59 34 14 24 20 4 10 ^ 7 51 54 17 33 32 23 19 10 11 21 50 27 14 4 45 3 47 13 8 14 1 17 ^ 10 23 450 11 12 21 40 55 13 44 56 3 23 40 8 36 18 4 30 23 856 12 13 21 30 57 13 24 54 3 5 8 57 50 18 19 31 23 12 39 13 14 21 20 34 13 4 39 2 36 28 9 19 32 18 34 14 23 15 56 14 15 21 9 47 12 44 11 2 12 49 9 41 4 18 48 39 23 18 50 16 16 20 58 35 12 23 30 1 49 9 10 2 27 19 2 45 23 21 18 16 17 20 47 12 2 38 1 25 27 10 23 40 19 16 31 23 23 22 17 18 20 35 11 41 34 1 1 45 10 44 44 19 29 58 23 26 1 18 19 20 22 37 11 20 19 38 3 11 5 36 19 43 6 23 26 15 19 20 20 9 51 10 58 53 S. 14 21 11 26 18 19 55 53 23 27 6 20 21 19 56 43 10 37 17 N. 9 20 11 46 48 20 8 20 23 27 30 21 23 19 43 12 10 15 31 33 1 12 7 8 20 20 26 23 27 29 23 23 19 29 19 9 53 36 56 41 12 27 15 20 32 12 23 27 4 23 24 19 15 4 9 31 31 1 20 18 12 47 10 20 43 36 23 26 16 24 25 19 28 9 9 19 1 43 54 13 6 52 20 54 40 23 25 25 26 18 45 31 8 46 58 2 728 13 26 21 21 5 21 23 23 21 26 27 18 30 14 8 24 59 2 30 58 13 45 37 21 15 41 23 21 17 27 28 18 14 37 8 1 53 2 54 26 14 4 40 21 26 38 23 18 48 28 29 17 58 40 3*17 50 14 23 28 21 3& 14 23 15 66 29 30 17 42 24 3 41 10 14 42 2 21 44 27 23 12 38 30 31 17 25 50 4 426 21 63 17 31 TABLE v.— Contmned. i July. August Sept Oct Not. Dec. • 1 o / ^/| o f // o / If o 1 n o 1 n^o 1 ft 1 23 8 56 18 6 40 8 23 33 3 5 ^ 14 22 19 21 47 34 1 2 23 4 49 17 51 30 8 144 32840 14 4130 215646 2 3 23 19 17 30 2 7 39 48, 3 51 56 15 27 22 5 34 3 4 22 55 25 17 20 17 7 17 44 4 15 9 15 19 9 22 13 55 4 5 22 50 17 4 16 6 55 32 4 38 20 15 37 37 22 21 51 5 6 '22 44 24 16 47 58 6 33 14! 5 1 27 15 55 49 22 29 21 6 7 22 38 18 16 31 23 6 10 49! 5 24 30 16 13 45 22 36 25 7 8 22 31 49 16 14 32 5 48 18 5 47 30 16 31 25 22 43 2 8 9 22 24 56 15 57 26 5 25 41 6 10 25 16 48 48 22 49 12 9 10 22 17 40 15 40 4 5 2 59 6 33 15 17 5 55 22 54 55 10 11 22 10 1 15 22 27 4 40 11 6 56 17 22 43 23 11 11 12 22 1 59 15 4 35 4 17 18 7 18 40 17 39 14 23 5 12 13 21 53 34 14 46 29 3 54 20 7 41 14 17 55 27 23 9 21 13 14 21 44 46 14 28 8 3 31 19 8 3 41 18 11 21 23 13 14 14 15 21 35 37 14 9 33 3 8 13 8 26 2 18 26 55 23 16 40 15 16 21 26 5 13 50 45 2 45 3 8 48 16 18 42 10 23 19 38 16 17 21 16 11 13 31 43 2 21 51 9 10 22 18 57 5 23 22 7 17 18 21 5 55 13 12 28 1 58 36 9 32 21 19 11 40 23 24 9 18 19 20 55 18 12 53 1 1 35 18 9 54 11 19 25 54 23 25 42 19 20 20 44 20 12 33 22 1 11 58 10 15 52 19 39 47 23 26 47 20 21 20 33 1 12 13 30 48 36 10 37 24 19 53 19 23 27 24 21 22 20 21 20 11 53 27 25 13 10 58 47 20 6 28 23 27 32 22 23 20 9 20 11 33 13 N. 1 49 11 19 59 20 19 15 23 27 13 23 24 19 56 59 11 12 48 S. 21 36 11 41 .1 20 31 40 23 26 24 24 25 19 44 19 10 52 12 45 1 12 1 53 20 43 42 23 25 8 25 26 19 31 18 10 31 26 1 8 27;12 22 33 20 55 21 23 23 23 26 27 19 17 59 10 10 31 1 31 5212 43 2 21 6 36 23 21 10 27 28 19 4 20! 9 49 25 1 55 16;i3 3 19 21 17 27 23 18 29 28 29 18 50 22 9 28 10 2 18 40;13 23 23 21 27 54 23 15 20 29 30 18 36 6 9 6 46 2 42 2 13 43 15.21 37 56 23 11 43 30 31 18 21 32 8 45 14 14 2 54 I 23 738 31 TABLE VI. Exhibitins the Sun's mean place in the Ecliptic, or its Longitudfly together with the Bight Ascension, for every day in the year. bL January. • February. March. ApriL Long. R. A. Long. R. A. Long. R. A. Long. R. A. o / o / o / o f o / o / o / o / 1 280 39 281 35 312 13 314 41 340 27 341 58 11 lO'lO 21 2 281 41 282 41 313 14 315 42 341 28 342 54 12 1511 16 3 282 42 283 48 314 14 316 42 342 28 343 50 13 14 12 10 4 283 43 284 54 315 15 317 43 343 28 344 46 14 13 13 5 5 284 44 286 316 16 318 43 344 28 345 41 15 12 'A a 6 285 45 287 6 317 17 319 44 345 28 346 37 16 11 14 54 7 286 46 288 11 318 17 320 46 346 28 347 32 17 10 15 49 8 287 48 289 17 319 18 321 44 347 28 348 28 18 9 16 44 9 288 49 290 22 320 19 322 43 348 27 349 23 19 8 17 39 10 289 50 291 28 321 19 323 43 349 27 350 18 20 6 18 34 11 290 51 292 33 322 20 324 41 350 27 351 13 21 5 19 29 12 291 52 293 38 323 21 325 40 351 27 352 22 4 20 24 13 292 53 294 43 324 21 326 40 352 27 353 4 23 3 21 19 14 293 54 295 47 325 22 327 38 353 26 353 59 24 1 22 14 15 294 55 296 52 326 22 328 37 354 26 354 53 25 00 23 9 16 295 57 297 56 327 23 329 35 355 26 355 48 25 59 24 5 37 296 58 299 328 23 330 33 356 25 356 43 26 57 25 18 297 59 300 4 329 24 331 31 357 25 357 38 27 56 25 66 19 299 301 8 330 24 332 29 358 24 358 32 28 54 26 61 20 300 1 302 12 331 25 333 27 359 24 359 27 29 53 27 47 21 301 2 303 15 332 25 334 24 000 24 22 30 51 28 43 22 302 3 304 19 333 26 335 21 1 23 1 16 31 50 29 39 23 303 i 305 22 334 26 336 18 2 22 2 10 32 48 30 35 24 30*4 5 306 25 335 26 337 '15 3 22 3 5 33 47 31 32 25 305 6 307 27 336 27 338 12 4 21 4 34 45 32 28 26 306 7 308 30 337 27 339 9 5 21 4 54 35 43 33 26 27 307 8 309 32 338 27 340 6 6 20 5 49 36 42 34 21 28 308 9 310 34 339 27 341 2 7 19 6 42 37 40 35 18 29 309 10 311 36 8 18 7 38 38 38 36 lis 30 310 11 312 38 9 18 8 32 39 36 37 ISI 'il 311 12 313 391 10 17 9 27 TABLE VI.— Cootmucd. ^^ May. June. July. Augusr. a Long. R. A. Long. R. A. Long. R, A. Long, f R. A o / o / o 1 o / o / o f o 7 o / 1 40 34 38 9 70 25 68 48 99 4 99 52 128 4C )131 5 2 41 32 39 6 71 23 69 50 100 1 100 54 129 37 ' 132 4 3 42 31 40 3 72 20 70 51 100 59 101 56 130 35 133 2 4 43 29 41 1 73 18 71 53 101 56 102 58 131 32 134 5 44 27 41 59 74 15 72 54 102 53.104 132 29 135 6 45 25 42 56 75 12 73 561103 50 105 74 581104 47 106 1 133 27 135 55 7 46 23 43 54 76 10 3 134 24 136 53 8 47 21 44 52 77 7 76 105 44 107 5 135 22|1 37 50 9 48 19 45 6 78 4 77 2 106 42 108 6 136 20 il38 47 10 49 16 46 49 79 2 78 4 107 39' 109 7 137 17 139 44 11 50 14 47 47 79 59 79 6 108 36' 110 9 138 15 140 41 12 51 12 48 46 80 56 80 8 109 33 111 10 139 12 141 38 13 52 10 49 45 81 54 81 10 110 31 112 11 140 10 142 34 14 53 8 50 44 82 51 82 13 111 28 113 12 141 8 143 31 15 54 6 51 42 83^48 83 15 112 25 114 13 142 5 144 27 16 55 3 52 42 84 46 84 17 113 22 115 13 143 3 145 24 17 56 1 53 41 85 43 85 20 114 20 116 14 144 1 146 20 " 18 56 59 54 41 86 40 86 22 115 17 117 14 144 59 147 16 19 57 57 55 41 87 37 87 24 116 14 118 15 145 56 148 12 20 58 54 56 41 88 35 88 27 117 11 119 15 146 54 149 7 21 59 52 57 41 89 32 89 30 118 9 120 15 147 52 150 3 22 60 50 58 41 90 29 90 32 119 6 121 15 148 50 150 58 23 61 47 59 41 91 26 91 34 120 3 122 14 149 48 151 54 24 62 45 60 41 92 24 92 36 121 1 123 14 150 46 152 49 25 63 43 61 42 93 21 93 39 121 58 124 14 151 44 153 44 26 64 40 62 42 94 18 94 41 122 55 125 13 152 42 154 39 27 65 38 63 43 95 15 95 43 123 53 126 12 153 39 155 34 28 66 35 64 44 96 13 96 46 124 50 127 11|154 37 10,155 35 155 29 29 67 33 65 45 97 10 97 48 125 48 128 157 24 30 68 30 66 46 98 7 98 50 126 45 129 9 156 34 138 18 31 .69 281 67 471 127 42 130 71 157 32 159 13 TABLE VI.— Continued. Iz as September. Long. 1 2 3 o / 158 30 159 28 160 26 4fl61 24 5 6 7 8 162 22 163 20 164 19 165 17 9 166 15 10 11 12 13 167 14 168 12 169 11 170 R. A. 14 371 15 172 6 16 173 5 17J174 3 18175 2 19176 1 20!l76 59 2d! 177 58 22)178 57 23 179 56 24 25 26 27 28 29 30 31 180 54 181 53 182 52 183 51 184 50 185 49 186 48 8 2 o f 160 161 161 55 162 51 163 45 164 39 165 33 166 27 167 21 168 15 169 9 170 3 October. Long. D f 187 47 188 46 189 45 J90 44 191 43 192 43 193 42 194 41 195 40 196 40 197 39 198 39 170 57)109 38 171 51 200 38 172 45 201 37 173 39|202 37 174 32:203 36 175 26 204 36 176 20 20feipe 177 14lg06 ^5 178 8!207 35 179 179 56 180 50 181 44 R. A. 187 188 188 189 190 191 192- 193 194 195 196 197 198 199 199 200 201 202 203 204 205 2J208 35 206 182 38 183 32 184 26 185 20 186 14 209 35 210 35 211 35 212 34 213 34 214 34 215 34 216 34 217 34 t 9 3 57 52 47 41 36 31 26 21 16 12 7 3 59 55 51 47 43 40 36 33 November. Long. 207 208 209 210 211 212 213 214 215 30 240 27 25 22 18 16 14 13 218 219 220 221 222 223 224 225 226 227 228 229 230 2^ 232' 233 234 235 236 237 238 239 f 34 35 35 35 35 35 36 36 36 37 37 37 38 38 39 39 40 41 41 42 R- A. 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 231 235 431236 43 237' December. Long. R. A 11248 10J249 9 8 241 242 243 20 244 245 246 247 44 45 45 46 47 48 49 50 238 239 240 241 242 243 244 246 250 251 252 253 254 255 256 257 258 260 261 262 263 264 265 966 267 268 269 270 271 272 273 274 8 8 7 8 8 8 9 10 11 13 14 16 IS 20 23 26 28 31 35 38 42 46 50 275 54276 58277 21278 1279 50 51 52 53 54 55 56 57 58 59 1 2 3 4 6 7 8 9 10 11 12 14 / 247 7 248 12 249 17 250 22 251 28 252 33 253 39 254 44 255 50 256 55 258 2 259 8 260 15 26121 262 27 263 34 264 40 265 47 266 54 268 269 7 270 14 . 271 20 15 272 27 10 273 34 17 274 40 18 275 47 19,276 53 21278 22279 6 23 280 13 TABLE VIL for 1835.